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Organocatalysis

ACh cover 24/2003The term organocatalysis describes the acceleration of chemical reactions through the addition of a substoichiometric quantity of an organic compound. The interest in this field has increased spectacularly in the last few years as result of both the novelty of the concept and, more importantly, the fact that the efficiency and selectivity of many organocatalytic reactions meet the standards of established organic reactions. Organocatalytic reactions are becoming powerful tools in the construction of complex molecular skeletons.[1,2]

[1] P. I. Dalko, L. Moisan,
Angew. Chem. 2001, 113, 3840; Angew. Chem. Int. Ed. 2001, 40, 3726
Angew. Chem. 2004, 116, 5248; Angew. Chem. Int. Ed. 2004, 43, 5138.

[2] Special issue of Adv. Synth. Catal. 2004, 346, Nr. 9-10.

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Catalytic Enantioselective Alkylation of Sulfenate Anions to Chiral Heterocyclic Sulfoxides Using Halogenated Pentanidium Salts

Phase transfer catalysis: Halogenated pentanidium salts are efficient phase-transfer catalysts for the enantioselective alkylation of sulfenate anions to sulfoxides with high enantioselectivity and high yield. Mechanistic studies indicate the ability of the catalysts to simultaneously activate/stabilize both nucleophile and electrophile through multiple noncovalent interactions (ion-pairing interaction, nonclassical hydrogen bonds, and halogen bonds).

Angew. Chem. Int. Ed., September 10, 2014, DOI: 10.1002/anie.201407512

Albrecht Berkessel, Somnath Das, Daniel Pekel, Jörg-M. Neudörfl
Anion-Binding Catalysis by Electron-Deficient Pyridinium Cations [Communication]

Anion-Binding Catalysis by Electron-Deficient Pyridinium Cations

A successful Trio: Pyridinium cations carrying three electron-withdrawing substituents catalyze the alkylation of α-halo ethers with silyl ketene acetals through Coulombic anion binding. This C-C bond formation proceeds efficiently at low temperatures and at low catalyst loading.

Angew. Chem. Int. Ed., September 10, 2014, DOI: 10.1002/anie.201403778

One-Pot Preparation of Chiral Carbacycles from Morita–Baylis–Hillman Carbonates by an Asymmetric Allylic Alkylation/Olefin Metathesis Sequence

A one-pot synthetic protocol for the regio- and stereoselective formation of highly substituted five- and six-membered carbacycles was developed. The two-step procedure includes an asymmetric allylic alkylation (AAA) of Morita–Baylis–Hillman (MBH) carbonates followed by a ring-closing alkene metathesis (RCM) reaction and affords the corresponding carbacycles in high yields with good enantioselectivity.

Eur. J. Org. Chem., September 9, 2014, DOI: 10.1002/ejoc.201402899

Organocatalyzed Cascade Aza-Michael/Michael Addition for the Asymmetric Construction of Highly Functionalized Spiropyrazolone Tetrahydroquinolines

One thing led to another: An organocatalyzed diastereo- and enantioselective cascade aza-Michael/Michael addition of 2-tosylaminoenones to unsaturated pyrazolones has been developed to afford novel chiral spiropyrazolone tetrahydroquinolines containing three contiguous stereocenters (see scheme).

Chem. Asian J., September 9, 2014, DOI: 10.1002/asia.201402706

N-Heterocyclic Carbene Catalyzed Cyclocondensation of α,β-Unsaturated Carboxylic Acids: Enantioselective Synthesis of Pyrrolidinone and Dihydropyridinone Derivatives

Into the mix: N-Heterocyclic carbenes (NHCs) catalyze the generation of α,β-unsaturated acyl azoliums from α,β-unsaturated carboxylic acids via in situ generated mixed anhydrides for the enantioselective [3+2] and [3+3] cyclocondensation with sulfonylated α-amino ketones and alkyl(aryl)imines, respectively. The corresponding pyrrolidinones and dihydropyridinones were isolated in good yields with high to excellent enantioselectivities.

Angew. Chem. Int. Ed., September 9, 2014, DOI: 10.1002/anie.201407469

Enantioselective Synthesis of Piperidines through the Formation of Chiral Mixed Phosphoric Acid Acetals: Experimental and Theoretical Studies

A rich seam: An enantioselective chiral phosphoric acid-catalyzed cyclization of unsaturated acetals has been utilized for the synthesis of functionalized chiral piperidines. The chiral enol ether products of these cyclizations undergo subsequent in situ enantioenrichment. A new computational method was utilized to elucidate the mechanism and stereoselectivity of this transformation. Cbz=benzyloxycarbonyl; S=resolution.

Angew. Chem. Int. Ed., September 4, 2014, DOI: 10.1002/anie.201405128

Proton-Transfer Polymerization (HTP): Converting Methacrylates to Polyesters by an N-Heterocyclic Carbene

Unsaturated polyesters are obtained specifically from dimethacrylates by a new step-growth polymerization catalyzed by an N-heterocyclic carbene.

Angew. Chem. Int. Ed., September 4, 2014, DOI: 10.1002/anie.201406630

James P. Phelan, Evan J. Patel, Jonathan A. Ellman
Catalytic Enantioselective Addition of Thioacids to Trisubstituted Nitroalkenes [Communication]

Catalytic Enantioselective Addition of Thioacids to Trisubstituted Nitroalkenes

High enantioselectivities and excellent yields are obtained in the first example of a catalytic enantioselective addition to and nitronate protonation of trisubstituted nitroalkenes, generating a tetrasubstituted carbon atom. Thioacids reacted with both activated and unactivated nitroalkenes. The 1,2-nitrothioacetate products can be readily converted in two steps to biomedically relevant 1,2-aminosulfonic acids without loss of enantiopurity.

Angew. Chem. Int. Ed., September 4, 2014, DOI: 10.1002/anie.201406971

Jan Zelenka, Tomáš Hartman, Kateřina Klímová, František Hampl, Radek Cibulka
Phase-Transfer Catalysis in Oxidations Based on the Covalent Bonding of Hydrogen Peroxide to Amphiphilic Flavinium Salts [Communication]

Phase-Transfer Catalysis in Oxidations Based on the Covalent Bonding of Hydrogen Peroxide to Amphiphilic Flavinium Salts

Flavin of the month: A new system for two-phase oxidations with diluted aqueous hydrogen peroxide that uses a flavinium phase-transfer catalyst (Fl+) is developed. The system uses both activation and the increasing lipophilicity of peroxide species by its covalent bonding to the amphiphilic flavinium salt.

ChemCatChem, September 3, 2014, DOI: 10.1002/cctc.201402533

Giorgos N. Papadopoulos, Dimitris Limnios, Christoforos G. Kokotos
Photoorganocatalytic Hydroacylation of Dialkyl Azodicarboxylates by Utilising Activated Ketones as Photocatalysts [Full Paper]

Photoorganocatalytic Hydroacylation of Dialkyl Azodicarboxylates by Utilising Activated Ketones as Photocatalysts

Lights on: Visible-light metal-free mediated hydroacylation of dialkyl azodicarboxylates was achieved by utilizing phenyl glyoxylic acid as the photocatalyst (see scheme).

Chem. Eur. J., September 3, 2014, DOI: 10.1002/chem.201403275

Afnan Al-Hunaiti, Minna Räisänen, Petri Pihko, Markku Leskelä, Timo Repo
Organocatalytic Oxidation of Secondary Alcohols Using 1,2-Di(1-naphthyl)-1,2-ethanediamine (NEDA) [Short Communication]

Organocatalytic Oxidation of Secondary Alcohols Using 1,2-Di(1-naphthyl)-1,2-ethanediamine (NEDA)

A nonmetal catalytic oxidation of alcohols with preferential oxidation of secondary alcohols by diamine is developed. 1,2-Di(1-naphthyl)-1,2-ethanediamine (NEDA) is used as catalyst to selectively oxidize secondary alcohols in the presence of TBHP as terminal oxidant. The chiral NEDA is also studied and shows promising enantioselectivity in oxidative kinetic resolution of racemic secondary alcohols with good to excellent ee values.

Eur. J. Org. Chem., August 27, 2014, DOI: 10.1002/ejoc.201402991

Julian Stiller, Dorota Kowalczyk, Hao Jiang, Karl Anker Jørgensen, Łukasz Albrecht
Novel Organocatalytic Activation of Unmodified Morita–Baylis–Hillman Alcohols for the Synthesis of Bicyclic α-Alkylidene-Ketones [Communication]

Novel Organocatalytic Activation of Unmodified Morita–Baylis–Hillman Alcohols for the Synthesis of Bicyclic α-Alkylidene-Ketones

Let’s go stereo: A novel activation mode of Morita–Baylis–Hillman alcohols by the formation of a H-bonding-iminium-ion is demonstrated for the first time. Merging such a strategy with well-recognized enamine activation enables the synthesis of bicyclic α-alkylidene-ketones. The developed reaction sequence proceeds in high yields and in a highly diastereo- and enantioselective manner for a wide variety of substrates (see graphic).

Chem. Eur. J., August 25, 2014, DOI: 10.1002/chem.201404468

Asymmetric Organocatalyzed Michael Addition of Nitromethane to a 2-Oxoindoline-3-ylidene Acetaldehyde and the Three One-Pot Sequential Synthesis of (−)-Horsfiline and (−)-Coerulescine

Potted products: (−)-Horsfiline and (−)-coerulescine were synthesized through three one-pot operations in 33 and 46 % overall yield, respectively. Key to the success was the efficient use of a diarylprolinol silyl ether to catalyze the asymmetric Michael addition of nitromethane to a 2-oxoindoline-3-ylidene acetaldehyde (see scheme; Bn=benzyl; TMS=trimethylsilyl). This allowed the all-carbon quaternary, spirocyclic carbon stereocenter to be constructed in good yield with excellent enantioselectivity.

Chem. Eur. J., August 25, 2014, DOI: 10.1002/chem.201403932

Pushpak Mizar, Alessandra Burrelli, Erika Günther, Martin Söftje, Umar Farooq, Thomas Wirth
Organocatalytic Stereoselective Iodoamination of Alkenes [Communication]

Organocatalytic Stereoselective Iodoamination of Alkenes

An unexplored class of chiral thiohydantoins can be used as efficient catalysts for iodoaminations while additives effect the regiochemistry. Also quaternary stereocenters can be easily generated with this metal-free, organocatalytic protocol.

Chem. Eur. J., August 22, 2014, DOI: 10.1002/chem.201404762

Ophélie Quinonero, Cyril Bressy, Xavier Bugaut
Organocatalytic Enantioselective Construction of Polyaromatic Architectures [Highlight]

Organocatalytic Enantioselective Construction of Polyaromatic Architectures

Aromatics in 3D. Organocatalysis is now reaching beyond the control of stereogenic centers and opens new possibilities for the construction of complex polyaromatic structures with either helical or axial chirality.

Angew. Chem. Int. Ed., August 21, 2014, DOI: 10.1002/anie.201406263

Organocatalytic Enantioselective Strecker Reaction of Imines Containing a Thiazole Moiety by Using a Cinchona-Based Squaramide Catalyst

An organocatalytic enantioselective Strecker reaction was developed for the synthesis of α-amino nitriles that contain a thiazole moiety by using a cinchona-based squaramide catalyst. The corresponding products were obtained in good to excellent yields (up to 99 %) with excellent enantioselectivities (up to 98 % ee) by starting from aromatic-substituted imines.

Eur. J. Org. Chem., August 21, 2014, DOI: 10.1002/ejoc.201402764

Xiao-Nan Zhang, Gen-Qiang Chen, Xiang-Ying Tang, Yin Wei, Min Shi
Phosphine-Catalyzed Annulations of 4,4-Dicyano-2-Methylenebut-3-enoates with Maleimides and Maleic Anhydride [Communication]

Phosphine-Catalyzed Annulations of 4,4-Dicyano-2-Methylenebut-3-enoates with Maleimides and Maleic Anhydride

Formalities: Novel phosphine-catalyzed [4+1] and formal [3+2] annulations of 4,4-dicyano-2-methylenebut-3-enoates with maleimides and maleic anhydride, respectively, have been developed. Maleimides serve as C1 synthons and maleic anhydride behaved as a C3 synthon to afford the corresponding compounds. A phosphinium-containing zwitterion is the key intermediate in both annulations.

Angew. Chem. Int. Ed., August 19, 2014, DOI: 10.1002/anie.201406100

Fluxionally Chiral DMAP Catalysts: Kinetic Resolution of Axially Chiral Biaryl Compounds

A catalyst for kinetic resolution: Chiral 4-dimethylaminopyridine catalysts with a fluxional group to relay stereochemical information from a fixed stereogenic center to the catalytic center promoted the acylative kinetic resolution of secondary alcohols and axially chiral biaryl compounds with high enantioselectivity (see scheme). The highly modular design of the chiral DMAP catalysts enables significant variation of their structure.

Angew. Chem. Int. Ed., August 14, 2014, DOI: 10.1002/anie.201406684

Ryosuke Matsubara, Yong-Soon Shin, Toshiyuki Shimada, Masahiko Hayashi
Revisiting the Saito Photochemical Reduction and the Development of a One-Pot Deoxygenation of Alcohols [Communication]

Revisiting the Saito Photochemical Reduction and the Development of a One-Pot Deoxygenation of Alcohols

Concentrate on this one: The Saito photochemical reduction of m-(trifluoromethyl)benzoates has been revisited. In contrast to the conventional conditions, the developed method eliminates the formation of alkene byproducts at high concentrations. Combining direct esterification and the Saito photochemical reduction, a one-pot deoxygenation process of alcohols has also been developed. LED=light-emitting diode; TsOH=4-toluenesulfonic acid.

Asian J. Org. Chem., August 11, 2014, DOI: 10.1002/ajoc.201402123

Mengnan Zhang, Tiezheng Jia, Haolin Yin, Patrick J. Carroll, Eric J. Schelter, Patrick J. Walsh
A New Class of Organocatalysts: Sulfenate Anions [Communication]

A New Class of Organocatalysts: Sulfenate Anions

Sulfenates take center stage: Sulfenate anions are known as highly reactive species in the organic arena. Now they premiere as organocatalysts: A sulfoxide/sulfenate (1–10 mol %) promotes the transformation of benzyl halides into trans-stilbenes under basic conditions (up to 99 % yield). CPME=cyclopentyl methyl ether.

Angew. Chem. Int. Ed., August 11, 2014, DOI: 10.1002/anie.201405996

Enantioselective Formation of All-Carbon Quaternary Stereocenters from Indoles and Tertiary Alcohols Bearing A Directing Group

Center on C: An efficient catalytic asymmetric intermolecular C-C bond-formation process to generate acyclic all-carbon quaternary stereocenters is described. The new asymmetric nucleophilic substitution of a range of racemic tertiary alcohols proceeds with excellent bond-formation efficiency and stereocontrol. The enantioenriched indole-containing products and their derivatives are prevalent in natural products and biologically active molecules.

Angew. Chem. Int. Ed., August 1, 2014, DOI: 10.1002/anie.201405252

Charles C. J. Loh, Pankaj Chauhan, Daniel Hack, Christian Lehmann, Dieter Enders
Rapid Asymmetric Synthesis of Highly Functionalized Indanols via a Michael/Henry Organocascade with Submol% Squaramide Catalyst Loadings [Update]

Sylvain Oudeyer, Jean-François Brière, Vincent Levacher
Progress in Catalytic Asymmetric Protonation [Microreview]

Progress in Catalytic Asymmetric Protonation

This review provides an overview of recent advances in catalytic enantioselective protonation of preformed enol derivatives and catalytically generated enolates or equivalents through various cascade reaction sequences giving access to a large range of enantioenriched compounds containing tertiary stereocentres.

Eur. J. Org. Chem., May 22, 2014, DOI: 10.1002/ejoc.201402213

Applications of Chiral Phosphine-Based Organocatalysts in Catalytic Asymmetric Reactions

Out with the old: The design and synthesis of new chiral phosphines, as well as their application in catalytic asymmetric reactions, have recently drawn a lot of attention. This review summarizes the advances in the field of enantioselective phosphine organocatalysis within the last couple of years.

Chem. Asian J. 2014, 9, No. 10, 2720-2734

Samaresh Chandra Sau, Sudipta Raha Roy, Swadhin K. Mandal
One-Pot Consecutive Catalysis by Integrating Organometallic Catalysis with Organocatalysis [Full Paper]

One-Pot Consecutive Catalysis by Integrating Organometallic Catalysis with Organocatalysis

One thing led to another... Organometallic catalysis and organocatalysis are integrated in the same reaction pot, starting with an abnormal N-heterocyclic carbene based copper catalyst. This catalyst acts as an efficient catalyst for a click reaction to provide a triazole, which acts as an efficient organocatalyst for different organic transformations in a consecutive fashion in the same reaction pot (see figure).

Chem. Asian J. 2014, 9, No. 10, 2806-2813

An Organocatalytic Azide–Aldehyde [3+2] Cycloaddition: High-Yielding Regioselective Synthesis of 1,4-Disubstituted 1,2,3-Triazoles

Metal-free click: A variety of commercially available aldehydes was used in the metal-free organo-click reaction with aryl azides to obtain 1,4-disubstituted 1,2,3-triazoles. The method constitutes an alternative to previously known metal-catalyzed azide–alkyne cycloaddition reactions (AAC), such as CuAAC, RuAAC, and IrAAC. DBU=1,8-diazabicyclo[5.4.0]undec-7-ene; DMSO=dimethyl sulfoxide.

Angew. Chem. Int. Ed. 2014, 53, No. 39, 10420-10424

Lihua Liao, Chang Shu, Minmin Zhang, Yijun Liao, Xiaoyan Hu, Yonghong Zhang, Zhijun Wu, Weicheng Yuan, Xiaomei Zhang
Highly Enantioselective [3+2] Coupling of Indoles with Quinone Monoimines Promoted by a Chiral Phosphoric Acid [Communication]

Highly Enantioselective [3+2] Coupling of Indoles with Quinone Monoimines Promoted by a Chiral Phosphoric Acid

Benzofuroindolines: The title reaction has been realized. A wide variety of benzofuroindolines have been prepared with moderate to good yields in moderate to excellent enantioselectivities. Ts=4-toluenesulfonyl.

Angew. Chem. Int. Ed. 2014, 53, No. 39, 10471-10475

A Metal-Free Three-Component Reaction for the Regioselective Synthesis of 1,4,5-Trisubstituted 1,2,3-Triazoles

Fully functionalized 1,2,3-triazoles were obtained by a metal-free three-component reaction. Simple and readily available building blocks were employed in this organocatalytic transformation, which gave the desired products in good yield and with high regioselectivity. Most of the synthesized triazoles were previously inaccessible.

Angew. Chem. Int. Ed. 2014, 53, No. 38, 10155-10159

Yujiro Hayashi, Yuya Kawamoto, Masaki Honda, Daichi Okamura, Shigenobu Umemiya, Yuka Noguchi, Takasuke Mukaiyama, Itaru Sato
Diphenylprolinol Silyl Ether Catalyzed Asymmetric Michael Reaction of Nitroalkanes and β,β-Disubstituted α,β-Unsaturated Aldehydes for the Construction of All-Carbon Quaternary Stereogenic Centers [Full Paper]

Diphenylprolinol Silyl Ether Catalyzed Asymmetric Michael Reaction of Nitroalkanes and β,β-Disubstituted α,β-Unsaturated Aldehydes for the Construction of All-Carbon Quaternary Stereogenic Centers

We like Mike: The Michael reaction of nitromethane to β,β-disubstituted α,β-unsaturated aldehydes catalyzed by diphenylprolinol silyl ether was developed to afford Michael adducts with all-carbon quaternary stereogenic centers and excellent enantioselectivity (see scheme). The E/Z isomerization of α,β-unsaturated aldehydes, the retro-Michael reaction, and the different reactivity between nitromethane and nitroethane are discussed.

Chem. Eur. J. 2014, 20, No. 38, 12072-12082

N-Heterocyclic Carbene Catalyzed Formal [3+2] Annulation Reaction of Enals: An Efficient Enantioselective Access to Spiro-Heterocycles

Ring, ring: A highly enantioselective formal [3+2] annulation of α,β-unsaturated aldehydes with azaaurones or aurone is catalyzed by an N-heterocyclic carbene (NHC) and generates spiro-heterocycles. The protocol represents a unique NHC activation-based approach to access spiro-heterocyclic derivatives bearing a quaternary stereogenic center with high optical purity.

Angew. Chem. Int. Ed. 2014, 53, No. 38, 10232-10236

Anthony Martin, Frédéric Robert, Daniel Taton, Henri Cramail, Jean-Marc Vincent, Yannick Landais
Organocatalyzed Step-Growth Polymerization through Desymmetrization of Cyclic Anhydrides: Synthesis of Chiral Polyesters [Full Paper]

Organocatalyzed Step-Growth Polymerization through Desymmetrization of Cyclic Anhydrides: Synthesis of Chiral Polyesters

Chirality on the go: Step-growth polymerization between prochiral bis-anhydrides and diols is triggered by a cinchona alkaloid based organocatalyst, affording new chiral polyesters in good yields with high enantioselectivities (see scheme). The enantioselectivity of the asymmetric polymerization was measured by chiral HPLC analysis of chiral bis-lactones obtained by a controlled depolymerization of the polyesters.

Chem. Eur. J. 2014, 20, No. 37, 11946-11953

Polyssena Renzi, Christel Kronig, Armando Carlone, Serap Eröksüz, Albrecht Berkessel, Marco Bella
Kinetic Resolution of Oxazinones: Rational Exploration of Chemical Space through the Design of Experiments [Full Paper]

Kinetic Resolution of Oxazinones: Rational Exploration of Chemical Space through the Design of Experiments

Rational optimization: Kinetic resolution of oxazinones has been studied as a model reaction to develop a sound strategy to achieve the best results with a rational approach rather than by trial-and-error (see scheme). With this strategy, chiral oxazinones can be resolved with ee values up to 99.6 % and ester products with ee values up to 90 % (selectivity factor up to S=98).

Chem. Eur. J. 2014, 20, No. 37, 11768-11775

Phosphoric Acid Catalyzed Desymmetrization of Bicyclic Bislactones Bearing an All-Carbon Stereogenic Center: Total Syntheses of (−)-Rhazinilam and (−)-Leucomidine B

Breaking symmetry: Achiral bislactones (1) undergo desymmetrization by reaction with alcohol in the presence of chiral imidodiphosphoric acids. The monoacids 2, having an all-carbon stereogenic center, were obtained in good to excellent yields and enantioselectivities. Concise total syntheses of (−)-rhazinilam and (−)-leucomidine B were subsequently developed using 2 as a common starting material.

Angew. Chem. Int. Ed. 2014, 53, No. 37, 9926-9930

Total Synthesis of (−)-Platensimycin by Advancing Oxocarbenium- and Iminium-Mediated Catalytic Methods

Relay tactics: The stereocontrolled assembly of the potent antibiotic (−)-platensimycin in 21 steps and 3.8 % yield from eugenol is described (see scheme; TBAF: tetrabutylammonium fluoride; Ts: toluene-4-sulfonyl). Highlights are 1) a rapid oxidative esterification of an acyl aromatic, 2) a reliable dialkylation protocol to form platensic acid, 3) a π-facial conjugate reduction of a dienone, 4) a TBAF-promoted alkylative dearomatization of a free phenol, and 5) a Friedel–Crafts closure of a free lactol.

Chem. Eur. J. 2014, 20, No. 36, 11556-11573

Diastereo- and Enantioselective Construction of a Bispirooxindole Scaffold Containing a Tetrahydro-β-carboline Moiety through an Organocatalytic Asymmetric Cascade Reaction

First class construction: The first catalytic asymmetric construction of a new class of bispirooxindole scaffold containing a tetrahydro-β-carboline moiety has been established through chiral phosphoric acid catalyzed three-component cascade Michael/Pictet–Spengler reactions of isatin-derived 3-indolylmethanols, isatins, and an amino ester, which afforded structurally complex and diverse bispirooxindoles with two stereogenic centers in excellent stereoselectivities (see scheme; BH*=chiral Brønsted acid, 1,1,2,2-TCE=1,1,2,2-tetrachloroethane; all >95:5 d.r., up to 98:2 e.r.).

Chem. Eur. J. 2014, 20, No. 36, 11382-11389

Paola Riente, Alba Matas Adams, Josep Albero, Emilio Palomares, Miquel A. Pericàs
Light-Driven Organocatalysis Using Inexpensive, Nontoxic Bi2O3 as the Photocatalyst [Communication]

Light-Driven Organocatalysis Using Inexpensive, Nontoxic Bi2O3 as the Photocatalyst

Now it's bismuth time! The asymmetric intermolecular α-alkylation of aldehydes with α-bromocarbonyl compounds can be achieved under visible-light irradiation by combining the second-generation MacMillan catalyst and an inexpensive, nontoxic, and commercially available Bi2O3 powder. This reaction also proceeded with high efficiency when the reaction vial was exposed to the morning sunlight in Tarragona, Spain.

Angew. Chem. Int. Ed. 2014, 53, No. 36, 9613-9616

Jun-An Xiao, Qi Liu, Ji-Wei Ren, Jian Liu, Rich G. Carter, Xiao-Qing Chen, Hua Yang
Highly Enantioselective Construction of Polycyclic Spirooxindoles by Organocatalytic 1,3-Dipolar Cycloaddition of 2-Cyclohexenone Catalyzed by Proline-Sulfonamide [Short Communication]

Highly Enantioselective Construction of Polycyclic Spirooxindoles by Organocatalytic 1,3-Dipolar Cycloaddition of 2-Cyclohexenone Catalyzed by Proline-Sulfonamide

The highly enantioselective construction of polycyclic spirooxindoles through 1,3-dipolar cycloaddition of cyclohexenone with azomethine ylides is achieved by employing prolinosulfonamides as the catalyst. This catalytic system essentially benefits from iminium activation and hydrogen-bonding formation induced by the prolinosulfonamides.

Eur. J. Org. Chem. 2014, No. 26, 5700-5704

Enantioselective Direct Bisvinylogous 1,6-Additions of β-Allyl-2-cyclohexenone to α,α-Dicyanodienes through Trienamine Catalysis

A highly enantioselective, direct ε-regioselective bisvinylogous 1,6-addition reaction of β-allyl-2-cyclohexenone to β-substituted α,α-dicyanodienes is developed through trienamine catalysis of a bifunctional primary amine–thiourea compound. Excellent enantioselectivity is obtained, and more complex cyclic frameworks can be efficiently constructed in a highly stereoselectivity manner. OFBA = o-fluorobenzoic acid.

Eur. J. Org. Chem. 2014, No. 27, 5906-5909

Marco Lombardo, Lucia Cerisoli, Elisabetta Manoni, Elisa Montroni, Arianna Quintavalla, Claudio Trombini
Properties and Reactivity of Conformationally Constrained Bicyclic Diarylprolinol Silyl Ethers as Organocatalysts [Full Paper]

Properties and Reactivity of Conformationally Constrained Bicyclic Diarylprolinol Silyl Ethers as Organocatalysts

Bicyclic silyl ether derivative 1a, which is easily prepared from trans-4-L-hydroxyproline, is much more stable toward protodesilylation than Jørgensen–Hayashi's catalyst 2a. Despite their structural analogy, 1a behaves as a very efficient catalyst in iminium chemistry, but is much less active than 2a in the enamine activation mode. Here, 1a exhibits a higher or equivalent level of stereocontrol.

Eur. J. Org. Chem. 2014, No. 27, 5946-5953

Remote Sulfonamido Group Enhances Reactivity and Selectivity for Asymmetric Michael Addition of Nitroalkanes to α,β-Unsaturated Aldehydes

Two birds with one stone: The pyrrolidine–camphorsulfonamide-based catalyst 1 a catalyzes the enantioselective conjugate addition of nitroalkanes to α,β-unsaturated aldehydes in the presence of 5 equivalents of water in iPrOH to give the corresponding chiral Michael adducts in good yields and high enantioselectivities (up to 99 % ee) with catalyst loading as low as 1 mol %.

Chem. Asian J. 2014, 9, No. 09, 2444-2448

Mareike C. Holland, Giel Berden, Jos Oomens, Anthony J. H. M. Meijer, Mathias Schäfer, Ryan Gilmour
Infrared Multiphoton Dissociation Spectroscopic Analysis of Noncovalent Interactions in Organocatalysis [Short Communication]

Infrared Multiphoton Dissociation Spectroscopic Analysis of Noncovalent Interactions in Organocatalysis

The first application of infrared multiphoton dissociation (IRMPD) spectroscopy to study noncovalent interactions in organocatalysis is reported. Valuable insight into the interactions associated with MacMillan-catalyst-derived α,β-unsaturated iminium ions can be derived in the absence of solvent or counterions. A preliminary structure–catalysis correlation is also disclosed.

Eur. J. Org. Chem. 2014, No. 26, 5675-5680

Selector-Induced Dynamic Deracemization of a Selectand-Modified Tropos BIPHEPO-Ligand: Application in the Organocatalyzed Asymmetric Double-Aldol-Reaction

Deracemization does the trick: The catalytic chiral resolution of tropos biarylphosphineoxides is combined with their high stereoinduction in asymmetric double-aldol-additions. The transient diastereomeric interaction of the modified biarylphosphineoxide was maximized by molecular design, which leads to an unusually high deracemization during HPLC.

Angew. Chem. Int. Ed. 2014, 53, No. 33, 8756-8760

Jordi Burés, Paul Dingwall, Alan Armstrong, Donna G. Blackmond
Rationalization of an Unusual Solvent-Induced Inversion of Enantiomeric Excess in Organocatalytic Selenylation of Aldehydes [Communication]

Rationalization of an Unusual Solvent-Induced Inversion of Enantiomeric Excess in Organocatalytic Selenylation of Aldehydes

Off the beaten path: Studies of an unusual inversion of the sense of enantioselectivity for the selenylation of aldehydes catalyzed by a diphenylprolinol ether catalyst provides support for a mechanistic concept beyond the simple steric model developed for enamine catalysis in these systems. A general role for downstream intermediates in selectivity outcomes in organocatalysis is discussed. TMS=trimethylsilyl.

Angew. Chem. Int. Ed. 2014, 53, No. 33, 8700-8704

Sébastien Prévost, Nathalie Dupré, Markus Leutzsch, Qinggang Wang, Vijay Wakchaure, Benjamin List
Catalytic Asymmetric Torgov Cyclization: A Concise Total Synthesis of (+)-Estrone [Communication]

Catalytic Asymmetric Torgov Cyclization: A Concise Total Synthesis of (+)-Estrone

A short circuit: An asymmetric Torgov cyclization, catalyzed by a novel, highly Brønsted acidic dinitro-substituted disulfonimide, is described. The reaction delivers the Torgov diene and various analogues with excellent yields and enantioselectivity. The method was applied in a very short synthesis of (+)-estrone.

Angew. Chem. Int. Ed. 2014, 53, No. 33, 8770-8773

Bangping Xiang, Kevin M. Belyk, Robert A. Reamer, Nobuyoshi Yasuda
Discovery and Application of Doubly Quaternized Cinchona-Alkaloid-Based Phase-Transfer Catalysts [Communication]

Discovery and Application of Doubly Quaternized Cinchona-Alkaloid-Based Phase-Transfer Catalysts

A doubly positive development: N,N'-Disubstituted cinchona alkaloids were found to be highly efficient phase-transfer catalysts for the assembly of stereogenic quaternary centers. In comparison to traditional cinchona-alkaloid phase-transfer catalysts they afforded substantial improvements in enantioselectivity and reactivity in intramolecular spirocyclization reactions at catalyst loadings as low as 0.3 mol % under mild conditions (see example).

Angew. Chem. Int. Ed. 2014, 53, No. 32, 8375-8378

Masashi Hayashi, Masaru Iwanaga, Noriyuki Shiomi, Daisuke Nakane, Hideki Masuda, Shuichi Nakamura
Direct Asymmetric Mannich-Type Reaction of α-Isocyanoacetates with Ketimines using Cinchona Alkaloid/Copper(II) Catalysts [Communication]

Direct Asymmetric Mannich-Type Reaction of α-Isocyanoacetates with Ketimines using Cinchona Alkaloid/Copper(II) Catalysts

The enantioselective direct Mannich-type reaction of ketimines with α-isocyanoacetates has been developed. Excellent yields and enantioselectivities were observed for the reaction of various ketimines and α-isocyanoacetates using cinchona alkaloid/Cu(OTf)2 and a base. Both enantiomers of the products could be obtained by using pseudoenantiomeric chiral catalysts. This process offers an efficient route for the synthesis of α,β-diamino acids.

Angew. Chem. Int. Ed. 2014, 53, No. 32, 8411-8415

Enantioselective Organocatalytic Michael/Aldol Sequence: Anticancer Natural Product (+)-trans-Dihydrolycoricidine

Taking steps: A stepwise organocatalytic Michael addition/aldol sequence is described involving secondary-amine-catalyzed regioselective addition of azidoacetone to cinnamaldehyde derivatives followed by intramolecular aldolization. Application of this route to aminocyclitols is demonstrated by a short, asymmetric synthesis of the anticancer natural product (+)-trans-dihydrolycoricidine.

Angew. Chem. Int. Ed. 2014, 53, No. 32, 8450-8454

Pushpak Mizar, Aragorn Laverny, Mohammad El-Sherbini, Umar Farid, Michael Brown, Florence Malmedy, Thomas Wirth
Enantioselective Diamination with Novel Chiral Hypervalent Iodine Catalysts [Communication]

Enantioselective Diamination with Novel Chiral Hypervalent Iodine Catalysts

The novel chiral iodoarene can be used as an efficient catalyst for the synthesis of diamines. Quaternary stereocenters can be easily generated with this metal-free, organocatalytic protocol (Cbz=benzyloxycarbonyl).

Chem. Eur. J. 2014, 20, No. 32, 9910-9913

Chiral Bifunctional Squaramide-Catalyzed Highly Enantioselective Michael Addition of Allomaltol to β,γ-Unsaturated α-Ketoesters

Be there or be square: An efficient approach for the enantioselective synthesis of kojic acid derivatives is developed. Under the catalysis of a chiral bifunctional squaramide incorporated into the (1R,2R)-1,2-diphenylethane-1,2-diamine scaffold, the Michael addition of allomaltol to a great number of β,γ-unsaturated α-ketoesters proceeds smoothly.

ChemCatChem 2014, 6, No. 08, 2298-2304

Highly Enantioselective Construction of Spirocyclopentaneoxindoles Containing Four Consecutive Stereocenters through an Organocatalytic Iminium–Enamine Cascade Reaction

Biologically important and synthetically challenging spirocyclopentaneoxindole derivatives containing four consecutive stereocenters, including one spiro quaternary center, are constructed with excellent enantio- and diastereomeric purities by an organocatalytic iminium–enamine cascade sequence between 3-substituted bifunctional oxindoles and α,β-unsaturated aldehydes under mild conditions.

Eur. J. Org. Chem. 2014, No. 24, 5139-5143

Joshua H. Jones, Chandrakumar Appayee, Stacey E. Brenner-Moyer
One-Pot Preparation of Enantiopure Fluorinated β-Amino Acid Precursors [Full Paper]

One-Pot Preparation of Enantiopure Fluorinated β-Amino Acid Precursors

An organocascade reaction enabling the transformation of enals into α-fluoro- and α,α-difluoro-β-amino aldehydes in a single flask is described. This organocascade reaction combines carbon–nitrogen and carbon–fluorine bond-forming reactions. It is thus a new approach to fluorinated β-amino acid precursors, and generates products not accessible by existing one-pot methods.

Eur. J. Org. Chem. 2014, No. 24, 5273-5280

Hazi Ahmad Beejapur, Vincenzo Campisciano, Paola Franchi, Marco Lucarini, Francesco Giacalone, Michelangelo Gruttadauria
Fullerene as a Platform for Recyclable TEMPO Organocatalysts for the Oxidation of Alcohols [Full Paper]

Fullerene as a Platform for Recyclable TEMPO Organocatalysts for the Oxidation of Alcohols

A great couple: Fullerene and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) moieties combined in molecular assemblies give rise to excellent catalysts for the oxidation of a wide range of alcohols. These hybrids are easily recycled and maintain their activity after seven cycles.

ChemCatChem 2014, 6, No. 08, 2419-2424

Sören Asmus , Stephan Beckendorf, Mercedes Zurro , Christian Mück-Lichtenfeld, Roland Fröhlich, Olga García Mancheño 
Influence of the Substitution and Conformation of C-H-Bond-Based Bis-Triazole Acceptors in Anion-Binding Catalysis [Full Paper]

Influence of the Substitution and Conformation of C-H-Bond-Based Bis-Triazole Acceptors in Anion-Binding Catalysis

Key structural parameters involved in the anion-binding process and the catalytic activity of the new family of C-H-bond-based, anion-binding bis-triazole catalysts BisTri were evaluated. These studies enabled the in silico design and identification of a new efficient BisTri catalyst (see scheme; R1=3,5-(CF3)2C6H3, R2=CN) for the alkylation reaction with an N-trityl pyridium salt as ionic electrophile.

Chem. Asian J. 2014, 9, No. 08, 2178-2186

Anneleen L. W. Demuynck, Maarten G. Goesten, Enrique V. Ramos-Fernandez, Michiel Dusselier, Jozef Vanderleyden, Freek Kapteijn, Jorge Gascon, Bert F. Sels
Induced Chirality in a Metal–Organic Framework by Postsynthetic Modification for Highly Selective Asymmetric Aldol Reactions [Communication]

Induced Chirality in a Metal–Organic Framework by Postsynthetic Modification for Highly Selective Asymmetric Aldol Reactions

Organocatalysis with MOFs: A practical synthesis route to chiral metal–organic frameworks is proposed that relies on an acid–base interaction between an acid linker and a chiral primary amino acid derived diamine organocatalyst. High ee values for the aldol condensation of linear ketones and aromatic aldehydes are reported.

ChemCatChem 2014, 6, No. 08, 2211-2214

Laura González, Jorge Escorihuela, Belén Altava, M. Isabel Burguete, Santiago V. Luis
Chiral Room Temperature Ionic Liquids as Enantioselective Promoters for the Asymmetric Aldol Reaction [Full Paper]

Chiral Room Temperature Ionic Liquids as Enantioselective Promoters for the Asymmetric Aldol Reaction

Chiral ionic liquids derived from natural amino acids are shown to be efficient solvents or additives for direct asymmetric aldol reactions. A match/mismatch effect between the configuration of the chiral ionic liquid and that of proline has been observed, with a higher enantioselectivity obtained for the (S)-proline/CIL 2 complex.

Eur. J. Org. Chem. 2014, No. 24, 5356-5363

Cecilia Martín-Santos, Carlos Jarava-Barrera, Sandra del Pozo, Alejandro Parra, Sergio Díaz-Tendero, Rubén Mas-Ballesté, Silvia Cabrera, José Alemán
Highly Enantioselective Construction of Tricyclic Derivatives by the Desymmetrization of Cyclohexadienones [Communication]

Highly Enantioselective Construction of Tricyclic Derivatives by the Desymmetrization of Cyclohexadienones

Breaking the mirror: In an asymmetric synthesis of tricyclic compounds containing a heterocyclic ring by the desymmetrization of cyclohexadienones, a large variety of substituents at different positions of the cyclohexadienone were tolerated, and the size of the heterocyclic ring could be varied. DFT calculations showed that the reaction proceeds through an asynchronous [4+2] cycloaddition (see scheme).

Angew. Chem. Int. Ed. 2014, 53, No. 31, 8184-8189

Dorine Belmessieri, Alix de la Houpliere, Ewen D. D. Calder, James E. Taylor, Andrew D. Smith
Stereodivergent Organocatalytic Intramolecular Michael Addition/Lactonization for the Asymmetric Synthesis of Substituted Dihydrobenzofurans and Tetrahydrofurans [Full Paper]

Stereodivergent Organocatalytic Intramolecular Michael Addition/Lactonization for the Asymmetric Synthesis of Substituted Dihydrobenzofurans and Tetrahydrofurans

You can have it both ways! A stereodivergent asymmetric Lewis base catalyzed Michael addition/lactonization of enone acids into substituted dihydrobenzofuran and tetrahydrofuran derivatives is reported, giving products with high d.r. and ee (see scheme).

Chem. Eur. J. 2014, 20, No. 31, 9762-9769

Mattia Riccardo Monaco, Sébastien Prévost, Benjamin List
Organocatalytic Asymmetric Hydrolysis of Epoxides [Communication]

Organocatalytic Asymmetric Hydrolysis of Epoxides

The natural strategy: Carboxylic acids were activated with chiral phosphoric acid catalysts and the mechanism of epoxide hydrolase served as a model for the asymmetric hydrolysis of meso-epoxides. This method was coupled with the Prilezhaev oxidation and the subsequent hydrolysis of the ester moiety to provide the first highly enantioselective anti-dihydroxylation of simple olefins.

Angew. Chem. Int. Ed. 2014, 53, No. 31, 8142-8145

Rebecca L. Davis, Julian Stiller, Tricia Naicker, Hao Jiang, Karl Anker Jørgensen
Asymmetric Organocatalytic Epoxidations: Reactions, Scope, Mechanisms, and Applications [Minireview]

Asymmetric Organocatalytic Epoxidations: Reactions, Scope, Mechanisms, and Applications

Pick your type: In the past several decades, highly useful epoxidation protocols have been developed with a variety of activation modes using a wide range of asymmetric organocatalysts. This review documents the rapid and expansive development in this area, thus providing a clear overview of the various catalyst types available for asymmetric organocatalytic epoxidations, as well as their mechanisms and applications.

Angew. Chem. Int. Ed. 2014, 53, No. 29, 7406-7426

Gloria Rassu, Vincenzo Zambrano, Luigi Pinna, Claudio Curti, Lucia Battistini, Andrea Sartori, Giorgio Pelosi, Giovanni Casiraghi, Franca Zanardi
Direct and Enantioselective Vinylogous Michael Addition of α-Alkylidenepyrazolinones to Nitroolefins Catalyzed by Dual Cinchona Alkaloid Thioureas [Update]

Catalytic Asymmetric α-Hydroxyamination of Carbonyls with N-Hydroxycarbamates Becomes Greener

The power of two: A highly enantio- and regioselective aminocatalytic and Lewis acid catalyzed α-hydroxyamination of β-keto esters and 1,3-diketones with N-hydroxycarbamates is realized in “one-pot” under aerobic conditions. The powerful dual catalysis strategy opens opportunities for developing new efficient organic transformations. Cbz=Benzyloxycarbonyl, Boc=tert-butoxycarbonyl.

ChemCatChem 2014, 6, No. 07, 1863-1865

Tyler J. Auvil, Andrew G. Schafer, Anita E. Mattson
Design Strategies for Enhanced Hydrogen-Bond Donor Catalysts [Microreview]

Design Strategies for Enhanced Hydrogen-Bond Donor Catalysts

Since initial reports of organocatalysis through hydrogen bonding interactions, a number of strategies have emerged to allow access to enhanced hydrogen-bond donor (HBD) organocatalysts. These strategies range from augmentation of existing HBDs to the design and synthesis of new HBD catalysts. The effects of recent dual HBD designs on catalyst performance are described.

Eur. J. Org. Chem. 2014, No. 13, 2633-2646

Organocatalytic β-Functionalization of Saturated Carbonyl Compounds—the State of the Art

Get straight to the point! The elusive and direct organocatalytic β-functionalization of saturated carbonyl compounds has been tackled by oxidative enamine catalysis, oxidative NHC catalysis and merging of photoredox catalysis with organocatalysis. This new activation mode expanded the horizons of chemical synthesis and offers new insight for organic transformations and complex molecule synthesis.

ChemCatChem 2014, 6, No. 05, 1183-1185

Yao Li, Xin Li, Jin-Pei Cheng
Catalytic Asymmetric Synthesis of Chiral Benzofuranones [Review]

The Alternative Route to Enantiopure Multicomponent Reaction Products: Biocatalytic or Organocatalytic Enantioselective Production of Inputs for Multicomponent Reactions

This review describes an approach to enantiopure products based on the enantioselective generation, through biocatalysis or organocatalysis, of chiral substrates for a multicomponent reaction (MCR). If the chiral substrates are able to control the newly formed stereogenic centers, this strategy allows fast and diversity-oriented entry to complex chiral substrates.

Eur. J. Org. Chem. 2014, No. 10, 2005-2015

Andrea Gualandi, Luca Mengozzi, Claire M. Wilson, Pier Giorgio Cozzi
Synergy, Compatibility, and Innovation: Merging Lewis Acids with Stereoselective Enamine Catalysis [Focus Review]

Synergy, Compatibility, and Innovation: Merging Lewis Acids with Stereoselective Enamine Catalysis

The Perfect Storm! Water facilitates catalyst turnover in enamine organocatalysis, and it is generated during enamine formation. A synergy between Lewis acids and organocatalysts allows for the development of new, selective, and innovative processes, but water-compatible Lewis acids must be employed that are capable of surviving and maintaining activity in the presence of water.

Chem. Asian J. 2014, 9, No. 04, 984-995

Suqing Zheng, Casi M. Schienebeck, Wei Zhang, Hao-Yuan Wang, Weiping Tang
Cinchona Alkaloids as Organocatalysts in Enantioselective Halofunctionalization of Alkenes and Alkynes [Focus Review]

Cinchona Alkaloids as Organocatalysts in Enantioselective Halofunctionalization of Alkenes and Alkynes

You say goodbye, I say halo: Derivatives of cinchona alkaloids are an important class of organocatalysts. Their applications in asymmetric halofunctionalization of alkenes and alkynes are summarized in this Focus Review. A wide range of nucleophiles, halogenation reagents, and substituted alkenes, alkynes, or enynes can participate in these reactions to afford diverse chiral building blocks.

Asian J. Org. Chem. 2014, 3, No. 04, 366-376

Chiral 1,1'-Binaphthyl-2,2'-Disulfonic Acid (BINSA) and Its Derivatives for Asymmetric Catalysis

BINSA, done that: The Brønsted acidity of catalysts is considered to be associated with their catalytic activity. Therefore, chiral 1,1'-binaphthyl-2,2-disulfonic acid (BINSA) has recently received much attention as a strong chiral Brønsted acid catalyst. This Focus Review summarizes the latest achievements in chiral BINSA chemistry from the perspective of their synthesis and their catalytic use in asymmetric organocatalysis.

Asian J. Org. Chem. 2014, 3, No. 04, 352-365

Haiying Du, Jean Rodriguez, Xavier Bugaut, Thierry Constantieux
Organocatalytic Enantioselective Multicomponent Synthesis of Pyrrolopiperazines [Update]

Frédéric-Georges Fontaine, Marc-André Courtemanche, Marc-André Légaré
Transition-Metal-Free Catalytic Reduction of Carbon Dioxide [Concept]

Transition-Metal-Free Catalytic Reduction of Carbon Dioxide

Less is more: Metal-free systems, including frustrated Lewis pairs (FLPs), have been shown to bind CO2. By reducing the Lewis acidity and basicity of the ambiphilic system, it is possible to generate active catalysts for the deoxygenative hydroboration of carbon dioxide to methanol derivatives with conversion rates comparable to those of transition-metal-based catalysts (see scheme).

Chem. Eur. J. 2014, 20, No. 11, 2990-2996

N-Heterocyclic Carbene Catalyzed Activation of Esters: A New Option for Asymmetric Domino Reactions

Esters—what else! A new strategy in NHC organocatalysis allows the α-, β- and γ-activation of saturated and unsaturated esters. The resulting acyl azolium intermediates efficiently participate in domino reactions with suitable substrates to generate synthetically valuable carbo- and heterocycles with very good diastereo- and excellent enantioselectivities.

Angew. Chem. Int. Ed. 2014, 53, No. 06, 1485-1487

Alejandro Parra, Silvia Reboredo
Chiral Hypervalent Iodine Reagents: Synthesis and Reactivity [Minireview]

Chiral Hypervalent Iodine Reagents: Synthesis and Reactivity

All about iodine: Chiral hypervalent iodine chemistry has been steadily increasing in importance in recent years. This Minieview catalogues enantioselective transformations triggered by chiral hypervalent iodine(III/V) reagents, in stoichiometric or catalytic quantities, highlighting the different reactivities in terms of yield and enantioselectivity. Moreover, the synthesis of the most remarkable and successful catalysts has been illustrated in detail.

Chem. Eur. J. 2013, 19, No. 51, 17244-17260

Feng Shi, Wei Tan, Hong-Hao Zhang, Mei Li, Qin Ye, Guan-Hua Ma, Shu-Jiang Tu, Guigen Li
Asymmetric Organocatalytic Tandem Cyclization/Transfer Hydrogenation: A Synthetic Strategy for Enantioenriched Nitrogen Heterocycles [Update]

Martin J. Lear, Yujiro Hayashi
Remote 1,6-Stereocontrol by Iminium-mediated Organocatalytic Events [Highlight]

Remote 1,6-Stereocontrol by Iminium-mediated Organocatalytic Events

Control freaks: Chiral amine catalysts prove to be highly proficient mediators in the asymmetric, polyconjugate addition of C-, N-, and S-based nucleophiles to acyclic dienals and cyclic dienones. For high 1,6-selectivities, the stereo spatial matching of the molecular orbitals and ionic charges of the reacting species are key. But can we widen the scope and how far can we go with remote, iminium-stereocontrol?

ChemCatChem 2013, 5, No. 12, 3499-3501

Yong Sup Lee, Md. Maqusood Alam, Rangappa S Keri
Enantioselective Reactions of N-Acyliminium Ions Using Chiral Organocatalysts [Focus Review]

Enantioselective Reactions of N-Acyliminium Ions Using Chiral Organocatalysts

Smells like team spirit: N-acylimium ions are important reactive intermediates for the enantioselective synthesis of nitrogen-containing compounds. This review summarizes the enantioselective reactions of N-acyliminium ions with two different chiral organocatalysts, thioureas (A) and BINOL-derived phosphoric acid derivatives (B).

Chem. Asian J. 2013, 8, No. 12, 2906-2919

Wuming Yan, Xiaodong Shi, Cheng Zhong
Secondary Amines as Lewis Bases in Nitroalkene Activation [Focus Review]

Secondary Amines as Lewis Bases in Nitroalkene Activation

Second to none: Secondary amines are well-known enamine and iminium catalysts that can also be used as Lewis bases for the activation of electron-deficient olefins. In this Focus Review, a series of systematic studies on activation of nitroolefins with secondary amines as Lewis bases that give different multicomponent condensation products are described. Asymmetric syntheses of heterocycles based on this strategy are also presented.

Asian J. Org. Chem. 2013, 2, No. 11, 904-914

Recent Advances in Organocatalytic Methods for Asymmetric C-C Bond Formation

A large number of organocatalytic processes are already well established in organic synthesis. Nevertheless, the number of publications in this field is still on the increase; new important results are produced constantly. This review gives a detailed overview of the latest developments and main streams in organocatalyzed asymmetric C-C bond formation of the last three years. It is intended to outline the most important current findings focused on especially new synthetic methodologies.

Chem. Eur. J. 2013, 19, No. 43, 14346-14396

Senthil Narayanaperumal, Daniel G. Rivera, Rodrigo C. Silva, Márcio W. Paixão
Terpene-Derived Bifunctional Thioureas in Asymmetric Organocatalysis [Review]

Terpene-Derived Bifunctional Thioureas in Asymmetric Organocatalysis

From pine resin to catalyst: The easily available rosin diterpene abietic acid has been transformed into a unique class of bifunctional thiourea catalysts that can also incorporate further substituents, thereby enabling either Lewis base or enamine activation modes. Their application in a wide range of stereoselective transformations has revealed the positive effect of this chiral and rigid skeleton on the catalytic performance of these hybrid thioureas.

ChemCatChem 2013, 5, No. 10, 2756-2773

Kazutaka Shibatomi, Akira Narayama
Catalytic Enantioselective α-Chlorination of Carbonyl Compounds [Focus Review]

Catalytic Enantioselective α-Chlorination of Carbonyl Compounds

Being the alpha: Despite the synthetic utility of chiral alkyl chlorides, catalytic methods for achieving enantioselective chlorination were only developed a decade ago. This Focus Review discusses the catalytic enantioselective α-chlorination of carbonyl compounds, as well as some stereospecific substitution reactions of the resulting optically active chlorides.

Asian J. Org. Chem. 2013, 2, No. 10, 812-823

Powerful Amino Acid Derived Bifunctional Phosphine Catalysts Bearing a Hydrogen Bond Donor in Asymmetric Synthesis

Phosphines and hydrogen bonding are good collaborators! Air-stable α-amino acids or dipeptide derived chiral phosphines bearing hydrogen-bond-donating and silicon-based bulky groups are powerful and versatile catalysts for a range of enantioselective processes, including [3+2] and [4+2] cycloadditions, allylic alkylations, Morita–Baylis–Hillman reactions, and Michael addition reactions. They represent a class of novel, economical, and practical chiral phosphine-based organocatalysts.

ChemCatChem 2013, 5, No. 10, 2775-2784

Simple Organic Molecules as Catalysts for the Enantioselective Synthesis of Amines and Alcohols

Valiant catalysis: Hoveyda et al. have developed a set of catalysts derived from valine for enantioselective syntheses. Reagents are inexpensive, allyl additions are scalable, harsh conditions are avoided, and reactions can be performed with 0.25 mol % catalyst in under 6 h at room temperature. The efficiency, economy, selectivity, and simplicity of the transformations and the range of boron reagents look to have sustained impact on future progress in amine and alcohol syntheses.

ChemCatChem 2013, 5, No. 10, 2805-2808

Recent Advances in the Use of Chiral Brønsted Acids as Cooperative Catalysts in Cascade and Multicomponent Reactions

When one catalyst meets another: Since chiral Brønsted acids catalysts were discovered more than a decade ago, they have become prevalent in organocatalysis. Researchers have recently used cooperative catalysis to improve existing transformations and discover new reactions. This Focus Review summarizes the achievements made in the field of asymmetric cascade/multicomponent reactions with the help of cooperative catalysis from chiral Brønsted acids.

Asian J. Org. Chem. 2013, 2, No. 10, 824-836

Christina Lohoelter, Magdalena Weckbecker, Siegfried R. Waldvogel
(–)-Isosteviol as a Versatile Ex-Chiral-Pool Building Block for Organic Chemistry [Microreview]

(–)-Isosteviol as a Versatile Ex-Chiral-Pool Building Block for Organic Chemistry

The inexpensive and readily available ex-chiral-pool building block (–)-isosteviol provides unique geometric features such as the rigid and concave arrangement of its functional groups. Consequently, this valuable architecture has found significant applications in various fields of organic chemistry.

Eur. J. Org. Chem. 2013, No. 25, 5539-5554

Nicola Kielland, Christopher J. Whiteoak, Arjan W. Kleij
Stereoselective Synthesis with Carbon Dioxide [Review]

Somayeh Mohammadi, Roghayeh Heiran, Raquel P. Herrera, Eugenia Marqués-López
Isatin as a Strategic Motif for Asymmetric Catalysis [Minireview]

Isatin as a Strategic Motif for Asymmetric Catalysis

Strategic move: Isatin as a core structure has inspired the development of useful catalytic strategies to give access to interesting molecular architectures with biological activity.

ChemCatChem 2013, 5, No. 08, 2131-2148

Recent Developments in Amine-catalyzed Non-asymmetric Transformations

Ready, amine, fire! Amine catalysis is a useful and well-studied method for constructing a wide variety of chiral scaffolds in asymmetric synthesis. However, organocatalysis with amines that is not centered on asymmetric transformations is also developing at a rapid rate. In this Focus Review, reports on amine catalyzed non-asymmetric transformations are examined.

Asian J. Org. Chem. 2013, 2, No. 07, 542-557

Gloria Rassu, Vincenzo Zambrano, Luigi Pinna, Claudio Curti, Lucia Battistini, Andrea Sartori, Giorgio Pelosi, Franca Zanardi, Giovanni Casiraghi
Direct Regio-, Diastereo-, and Enantioselective Vinylogous Michael Addition of Prochiral 3-Alkylideneoxindoles to Nitroolefins [Update]

Catherine Gomez, Jean-François Betzer, Arnaud Voituriez, Angela Marinetti
Phosphine Organocatalysis in the Synthesis of Natural Products and Bioactive Compounds [Minireview]

Phosphine Organocatalysis in the Synthesis of Natural Products and Bioactive Compounds

From all natural to bioactive: This review shows that organocatalytic methods based on the use of nucleophilic phosphorus catalysts have been successfully applied as key steps in the formal or total synthesis of complex natural products. These methods also afford suitable tools for the constitution of either focused or diversity-oriented-synthesis inspired libraries of small molecules for biological screening.

ChemCatChem 2013, 5, No. 05, 1055-1065

Organocatalyzed Carbonyl–Olefin Metathesis

The heat is on: A new [3+2] cycloaddition/cycloreversion strategy allows for catalytic and thermally allowed carbonyl–olefin metathesis (see scheme). This strategy opens opportunities for new developments in the field of carbonyl–olefin metathesis, which traditionally relied on stoichiometric amounts of transition-metal reagents or photochemical promotion.

Angew. Chem. Int. Ed. 2013, 52, No. 17, 4524-4525

Seiji Shirakawa, Keiji Maruoka
Recent Developments in Asymmetric Phase-Transfer Reactions [Review]

Recent Developments in Asymmetric Phase-Transfer Reactions

Work in process: The variations in the synthetic applications of phase-transfer reactions between 2006 and the middle of 2012 have been summarized to show the recent progress made in this field. The reactions have been applied to the synthesis of biologically active natural products and the large-scale preparation of drugs. The conceptually new catalyst design, reaction system, and reaction mode are also described.

Angew. Chem. Int. Ed. 2013, 52, No. 16, 4312-4348

Suman De Sarkar, Anup Biswas, Ramesh C. Samanta, Armido Studer
Catalysis with N-Heterocyclic Carbenes under Oxidative Conditions [Concept]

Catalysis with N-Heterocyclic Carbenes under Oxidative Conditions

Cascading down: Reaction of an aldehyde with an NHC provides the corresponding Breslow intermediate A, which can be readily oxidized with various organic and inorganic oxidants to give the acylazolium ion B (see scheme). Intermediate B can react with various nucleophiles either at the 2 or 4-position. With enals as starting aldehydes, elegant cascade processes have been developed using oxidative carbene catalysis.

Chem. Eur. J. 2013, 19, No. 15, 4664-4678

Jin-Xin Zhang, Nai-Kai Li, Zhao-Min Liu, Xiao-Fei Huang, Zhi-Cong Geng, Xing-Wang Wang
Enantioselective Synthesis of Unsymmetrical Diaryl-Substituted Spirocyclohexanonepyrazolones through a Cascade [4+2] Double Michael Addition [Update]

Rafael Gramage-Doria, Joost N. H. Reek
Organocatalysis in Confined Spaces [Highlight]

Organocatalysis in Confined Spaces

Strap in with organocatalysis: Organocatalysis can often give rise to unprecedented selectivities by encapsulation of the catalytic active site in an analogous manner as enzymes. Catalyst encapsulation can be considered as a powerful strategy for achieving unique transformations in a very efficient way.

ChemCatChem 2013, 5, No. 03, 677-679

Mechanism of Diphenylprolinol Silyl Ether Catalyzed Michael Addition Revisited—but Still Controversial

Two views: The mechanism of the conjugate addition of linear aldehydes to nitro olefins has been investigated by two research groups. In spite of extensive experimental data, important questions remain unanswered (see scheme; TMS=trimethylsilyl, En=enamine).

Angew. Chem. Int. Ed. 2013, 52, No. 08, 2160-2162

Gonzalo de Gonzalo, Marco W. Fraaije
Recent Developments in Flavin-based Catalysis [Minireview]

Recent Developments in Flavin-based Catalysis

What to do with vitamin B2: Flavins are ubiquitous cofactors for enzymes and have been explored extensively as organocatalysts. Recent developments in the synthesis and use of flavin derivatives are discussed in this Minireview.

ChemCatChem 2013, 5, No. 02, 403-415

Asymmetric Organocatalytic Addition Reactions of Maleimides: A Promising Approach Towards the Synthesis of Chiral Succinimide Derivatives

Taking the Michael: Recent progress in asymmetric organocatalysis has led to the development of several asymmetric transformations that employ various substrates. Among these substrates, maleimides have emerged as excellent Michael acceptors, dienophiles, and dipolarophiles. In this Focus Review we highlight the advances in the asymmetric synthesis of succinimide derivatives.

Chem. Asian J. 2013, 8, No. 02, 328-346

Asymmetric Counteranion-Directed Catalysis: Concept, Definition, and Applications

Opposites attract: This simple realization is the basis for asymmetric counteranion-directed catalysis (ACDC). All reactions proceeding via cationic intermediates are accompanied by a counteranion. Inducing high enantioselectivities in these reactions merely by ion pairing with an enantiomerically pure counteranion has been achieved for the first time during recent years.

Angew. Chem. Int. Ed. 2013, 52, No. 02, 518-533

© Wiley-VCH 2013.