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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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Phase-Transfer-Catalyzed Asymmetric SNAr Reaction of α-Amino Acid Derivatives with Arene Chromium Complexes

Increased substrate scope in phase-transfer-catalyzed asymmetric SNAr reactions was achieved by the use of arene chromium complexes as electrophiles. An efficient asymmetric synthesis of α,α-disubstituted α-amino acids containing various aromatic substituents is shown. PTC=phase-transfer catalyst.

Angew. Chem. Int. Ed., November 20, 2014, DOI: 10.1002/anie.201409065

Michal Majek, Axel Jacobi von Wangelin
Metal-Free Carbonylations by Photoredox Catalysis [Communication]

Metal-Free Carbonylations by Photoredox Catalysis

A metal-free and base-free carbonylation has been developed which affords primary, secondary, and tertiary alkyl benzoates under irradiation with visible light in the presence of eosin Y as a photocatalyst. The mechanism has been studied by spectroscopic, theoretical, and preparative methods, and appears to involve intermediate aryl and aroyl radical species as well as a light-driven one-electron redox cycle without any sacrificial redox partner.

Angew. Chem. Int. Ed., November 20, 2014, DOI: 10.1002/anie.201408516

Asymmetric Dearomatization of β-Naphthols through an Amination Reaction Catalyzed by a Chiral Phosphoric Acid

Useful skeletons: An electrophilic amination reaction catalyzed by chiral phosphoric acid is the basis for a highly efficient asymmetric dearomatization of naphthols. This protocol provides functionalized β-naphthalenone compounds with a chiral quaternary carbon center in excellent yields and enantioselectivity. These motifs are found in various biologically active natural products and therapeutic reagents.

Angew. Chem. Int. Ed., November 20, 2014, DOI: 10.1002/anie.201409756

Mohammed Kadraoui, Thibault Maunoury, Zoubir Derriche, Stéphane Guillarme, Christine Saluzzo
Isohexides as Versatile Scaffolds for Asymmetric Catalysis [Microreview]

Isohexides as Versatile Scaffolds for Asymmetric Catalysis

Two series of dianhydrohexitol derivatives, the first preserving the original bis-fused THF backbones and the second originating from single THF ring-opening reactions, are used as asymmetric ligands in organometallic catalysis or as asymmetric organocatalysts. Their synthesis and their application in different asymmetric reactions for the formation of C–H, C–C, C–N, and C–S bonds are discussed.

Eur. J. Org. Chem., November 17, 2014, DOI: 10.1002/ejoc.201402851

Enamine/Enolate-Mediated Organocatalytic Azide–Carbonyl [3+2] Cycloaddition Reactions for the Synthesis of Densely Functionalized 1,2,3-Triazoles

Organocatalytic click! Recent advances in the metal-free enamine/enolate-mediated azide–carbonyl [3+2] cycloaddition reaction are discussed. These approaches require neither a metal catalyst nor alkyne substrates. Owing to the ready availability of carbonyl compounds, these methods thus offer excellent alternatives for the synthesis of 1,4-/1,5-disubstituted and 1,4,5-trisubstituted 1,2,3-triazoles.

Angew. Chem. Int. Ed., November 17, 2014, DOI: 10.1002/anie.201409410

N-Heterocyclic Carbenes Supported on Vinylic Addition Polynorbornene: A Recyclable and Recoverable Organocatalyst

Three in one to ease organocatalysis: A robust, tunable, and recyclable organocatalytic system has been prepared by anchoring N-heterocyclic carbenes on an all-aliphatic vinylic addition polynorbornene (VA-PNB) scaffold. These three features make this heterogeneous NHC-based organocatalyst most convenient.

ChemCatChem, November 13, 2014, DOI: 10.1002/cctc.201402767

Joyram Guin, Qinggang Wang, Manuel van Gemmeren, Benjamin List
The Catalytic Asymmetric Abramov Reaction [Communication]

The Catalytic Asymmetric Abramov Reaction

A chiral disulfonimide catalyst is used to achieve the first catalytic enantioselective Abramov reaction. Several functionalized α-hydroxy phosphonates were synthesized in good yields and with excellent enantiomeric ratios of up to >99:1. The process was shown to be scalable and up to 1 g of starting material could be employed under mild reaction conditions.

Angew. Chem. Int. Ed., November 13, 2014, DOI: 10.1002/anie.201409411

N-Heterocyclic Carbene Catalyzed Enantioselective α-Fluorination of Aliphatic Aldehydes and α-Chloro Aldehydes: Synthesis of α-Fluoro Esters, Amides, and Thioesters

Two roles for NFSI: The N-heterocyclic carbene (NHC) catalyzed asymmetric fluorination of readily available simple aliphatic aldehydes, α-chloro aldehydes, and even alcohols proceeds via azolium enolates and yields a wide range of α-fluoro esters, amides, and thioesters with excellent enantioselectivity. N-Fluorobenzenesulfonimide (NFSI) acts as both a fluorinating reagent and an oxidant in this transformation.

Angew. Chem. Int. Ed., November 13, 2014, DOI: 10.1002/anie.201409961

Rosaria Schettini, Brunello Nardone, Francesco De Riccardis, Giorgio Della Sala, Irene Izzo
Cyclopeptoids as Phase-Transfer Catalysts for the Enantioselective Synthesis of α-Amino Acids [Short Communication]

Cyclopeptoids as Phase-Transfer Catalysts for the Enantioselective Synthesis of α-Amino Acids

Cyclopeptoids are a novel class of efficient and tunable chiral macrocyclic phase-transfer catalyts. Screening of catalysts for the enantioselective alkylation of N-(diphenylmethylene)glycine tert-butyl ester shows the crucial role of N-arylmethyl residues.

Eur. J. Org. Chem., November 10, 2014, DOI: 10.1002/ejoc.201403224

Adrien Quintard, Diana Cheshmedzhieva, Maria del Mar Sanchez Duque, Anouk Gaudel-Siri, Jean-Valère Naubron, Yves Génisson, Jean-Christophe Plaquevent, Xavier Bugaut, Jean Rodriguez, Thierry Constantieux
Origin of the Enantioselectivity in Organocatalytic Michael Additions of β-Ketoamides to α,β-Unsaturated Carbonyls: A Combined Experimental, Spectroscopic and Theoretical Study [Full Paper]

Origin of the Enantioselectivity in Organocatalytic Michael Additions of β-Ketoamides to α,β-Unsaturated Carbonyls: A Combined Experimental, Spectroscopic and Theoretical Study

From theory to practise: The mechanism of asymmetric organocatalysed Michael addition of β-ketoamides to enones was studied theoretically, demonstrating for the first time the unique role of the hydrogen atom of the amide in controlling both the reactivity and the enantioselectivity (see scheme). Additional reactions afforded original spiro hemiaminals, taking advantage of the reactivity of the Michael adducts with acrolein. Post-functionalisation led to valuable enantioenriched glutarimides and pyridones.

Chem. Eur. J., November 7, 2014, DOI: 10.1002/chem.201404481

Yan Liu, Xiaobing Xi, Chengcheng Ye, Tengfei Gong, Zhiwei Yang, Yong Cui
Chiral Metal–Organic Frameworks Bearing Free Carboxylic Acids for Organocatalyst Encapsulation [Communication]

Chiral Metal–Organic Frameworks Bearing Free Carboxylic Acids for Organocatalyst Encapsulation

Two chiral carboxylic acid functionalized micro- and mesoporous metal–organic frameworks (MOFs) are constructed. The mesoporous MOF functions as a host for encapsulation of an enantiopure organic amine by acid–base interactions. The organocatalyst-loaded MOF is an efficient and recyclable heterogeneous catalyst for asymmetric direct aldol reactions, with significantly enhanced stereoselectivity relative to the homogeneous organocatalyst.

Angew. Chem. Int. Ed., November 7, 2014, DOI: 10.1002/anie.201408896

Synthesis and Evaluation of (S)-Proline-Containing α,β-Dipeptides as Organocatalysts in Solvent-Free Asymmetric Aldol Reactions Under Ball-Milling Conditions

A crushing victory: The organocatalytic activity of α,β-dipeptides 1 ac was evaluated in the asymmetric aldol reaction between ketones 2 and aldehydes 3. The best results in terms of yield and stereoselectivity were obtained under solvent-free conditions with ball-milling activation.

Asian J. Org. Chem., November 6, 2014, DOI: 10.1002/ajoc.201402170

Kerem Goren, Jeny Karabline-Kuks, Yael Shiloni, Einav Barak-Kulbak, Scott J. Miller, Moshe Portnoy
Multivalency as a Key Factor for High Activity of Selective Supported Organocatalysts for the Baylis–Hillman Reaction [Full Paper]

Multivalency as a Key Factor for High Activity of Selective Supported Organocatalysts for the Baylis–Hillman Reaction

Quantity into quality: A very strong manifestation of a positive multivalency effect on the catalytic activity is observed in dendritic polymer-supported catalysts, based on N-alkylimidazoles, in the Baylis–Hillman reaction (see scheme). Tethering the catalytically active units to a dendritic spacer enhances the activity per unit dramatically, sometimes by an order of magnitude.

Chem. Eur. J., November 5, 2014, DOI: 10.1002/chem.201404560

An Enolate-Mediated Organocatalytic Azide–Ketone [3+2]-Cycloaddition Reaction: Regioselective High-Yielding Synthesis of Fully Decorated 1,2,3-Triazoles

Fully functionalized 1,2,3-triazoles were synthesized by a metal-free clicking through an enolate-mediated organocatalytic azide–ketone [3+2]-cycloaddition (OrgAKC) reaction. Very simple and readily available aryl azides and enolizable arylacetones/deoxybenzoins were employed in this organocatalytic transformation (see scheme).

Chem. Eur. J., November 3, 2014, DOI: 10.1002/chem.201405501

Qiying Zhang, Xiuling Cui, Lianmei Chen, Haitao Liu, Yangjie Wu
Syntheses of Chiral Ferrocenophanes and Their Application to Asymmetric Catalysis [Short Communication]

Syntheses of Chiral Ferrocenophanes and Their Application to Asymmetric Catalysis

The synthesis of ferrocenophane–amines is developed. Compound L1 can be used as a ligand in the the copper-catalyzed oxidative coupling of 3-hydroxy-2-naphthoate to give the product in good yield with up to 92 % ee, and it also efficiently catalyzes the asymmetric Michael addition reaction as an organocatalyst.

Eur. J. Org. Chem., October 30, 2014, DOI: 10.1002/ejoc.201402985

One-Pot Synthesis of Tri- and Tetrasubstituted Pyridines by Sequential Ring-Opening/Cyclization/Oxidation of N-Arylmethyl 3-Aziridinylpropiolate Esters

Small ring, big ring: A novel strategy for the one-pot synthesis of substituted pyridines from N-arylmethyl 3-aziridinylpropiolate esters is described. The method employs a three-step procedure including the formation of allenyl imines, phosphine-catalyzed cyclization, and subsequent oxidation of the dihydropyridines. Depending on the reaction conditions of the final oxidation step, tri- and tetrasubstituted pyridines can be selectively produced.

Angew. Chem. Int. Ed., October 29, 2014, DOI: 10.1002/anie.201409015

Stereocontrolled Construction of the 3,4-Dihydrothiacarbazol-2(9H)-one Skeleton by Using Bifunctional Squaramide-Catalyzed Cascade Reactions

An efficient process for the enantioselective synthesis of optically active 3,4-dihydrothiacarbazol-2(9H)-one derivatives has been developed The cascade Michael addition/thiolysis reactions of 9-methylindoline-2-thiones and N-alkenoylphthalimides were promoted by a chiral bifunctional squaramide catalyst to give the desired products in acceptable yields with 54–98 % ee.

Eur. J. Org. Chem., October 29, 2014, DOI: 10.1002/ejoc.201403078

Chiral Squaramide-Catalyzed Sulfa-Michael/Aldol Cascade for the Asymmetric Synthesis of Spirocyclic Tetrahydrothiophene Chromanone Derivatives

A bifunctional squaramide-catalyzed sulfa-Michael/aldol cascade reaction between benzylidenechroman-4-ones and 1,4-dithiane-2,5-diol has been developed. This reaction enables facile asymmetric access to chiral spirocyclic tetrahydrothiophene chromanone derivatives with three contiguous stereocenters in high to excellent yields (up to 99 %) and with high enantioselectivities (up to 92 % ee).

Eur. J. Org. Chem., October 28, 2014, DOI: 10.1002/ejoc.201402889

Yujiro Hayashi, Daichi Okamura, Tatsuya Yamazaki, Yasuto Ameda, Hiroaki Gotoh, Seiji Tsuzuki, Tadafumi Uchimaru, Dieter Seebach
A Theoretical and Experimental Study of the Effects of Silyl Substituents in Enantioselective Reactions Catalyzed by Diphenylprolinol Silyl Ether [Full Paper]

A Theoretical and Experimental Study of the Effects of Silyl Substituents in Enantioselective Reactions Catalyzed by Diphenylprolinol Silyl Ether

Typecast: Reactions catalyzed by diphenylprolinol silyl ether can be categorized into three types (see figure): two involve an iminium ion intermediate, such as for a Michael-type reaction (type A) and a cycloaddition reaction (type B), and one proceeds via an enamine intermediate (type C). In type A, good enantioselectivity is realized if a catalyst with a bulky silyl moiety is employed. In types B and C, good enantioselectivity is obtained even when the silyl group is less bulky.

Chem. Eur. J., October 27, 2014, DOI: 10.1002/chem.201403514

Asymmetric Disulfonimide-Catalyzed Synthesis of δ-Amino-β-Ketoester Derivatives by Vinylogous Mukaiyama–Mannich Reactions

Lewis acid catalysis: A chiral disulfonimide (DSI) serves as a highly efficient precatalyst for vinylogous Mukaiyama–Mannich reactions of a readily available silyloxydiene with protected imines, delivering δ-amino-β-ketoesters. The synthetic utility of the reaction is illustrated by the preparation of valuable enantiomerically enriched building blocks and the formal synthesis of (−)-lasubin.

Angew. Chem. Int. Ed., October 27, 2014, DOI: 10.1002/anie.201407532

Guillem Valero, Josep M. Ribó, Albert Moyano
A Closer Look at Spontaneous Mirror Symmetry Breaking in Aldol Reactions [Full Paper]

A Closer Look at Spontaneous Mirror Symmetry Breaking in Aldol Reactions

Mirror, mirror on the wall! HPLC monitoring of the aldol reaction between 4-nitrobenzaldehyde and acetone (see figure) in the absence of a chiral catalyst reveals that spontaneous mirror symmetry breaking takes place initially in about 50 % of the reactions. A novel coupled reaction network that involves indirect autocatalysis and does not require heterochiral inhibition in the aldol product can explain this behavior.

Chem. Eur. J., October 24, 2014, DOI: 10.1002/chem.201404497

Chiral Ammonium Betaine-Catalyzed Highly Stereoselective Aza-Henry Reaction of α-Aryl Nitromethanes with Aromatic N-Boc Imines

What we need is tolerance: A highly stereoselective aza-Henry reaction of α-aryl nitromethanes with aromatic N-Boc imines was established by using C1-symmetric chiral ammonium betaine as a bifunctional organic base catalyst. The reaction tolerated various substituted aryl groups for both imines and nitromethanes, and a series of precursors for the synthesis of unsymmetrical anti-1,2-diaryl ethylenediamines was provided.

Chem. Asian J., October 22, 2014, DOI: 10.1002/asia.201402943

Lewis Base Catalyzed Aerobic Oxidative Intermolecular Azide–Zwitterion Cycloaddition

The works: The discovery of a novel aerobic oxidative intermolecular azide–zwitterion reaction catalyzed by an organocatalyst is presented. It is demonstrated that the merger of the Lewis base 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and electron-deficient olefins generates reactive zwitterion intermediates, which readily participate in cycloaddition reactions with an array of azides, thus providing facile entry to fully or highly substituted 1,2,3-triazole frameworks.

Angew. Chem. Int. Ed., October 15, 2014, DOI: 10.1002/anie.201408265

Junshan Tian, Jiankang Zhong, Yunsheng Li, Dawei Ma
Organocatalytic and Scalable Synthesis of the Anti-Influenza Drugs Zanamivir, Laninamivir, and CS-8958 [Communication]

Organocatalytic and Scalable Synthesis of the Anti-Influenza Drugs Zanamivir, Laninamivir, and CS-8958

A strategy to combat the flu: The anti-influenza drugs zanamivir and laninamivir (see structures) were synthesized in only 13 steps from inexpensive D-araboascorbic acid by the use of an organocatalytic Michael addition and a metal-catalyzed anti-selective Henry reaction as key transformations. This cost-effective, straightforward, and efficient approach enabled the synthesis of more than 3.5 g of zanamivir.

Angew. Chem. Int. Ed., October 14, 2014, DOI: 10.1002/anie.201408138

Antoine Buchard, David R. Carbery, Matthew G. Davidson, Petya K. Ivanova, Ben J. Jeffery, Gabriele I. Kociok-Köhn, John P. Lowe
Preparation of Stereoregular Isotactic Poly(mandelic acid) through Organocatalytic Ring-Opening Polymerization of a Cyclic O-Carboxyanhydride [Communication]

Preparation of Stereoregular Isotactic Poly(mandelic acid) through Organocatalytic Ring-Opening Polymerization of a Cyclic O-Carboxyanhydride

Controlling tactic(s): The use of pyridine alone as organocatalyst of the ring-opening polymerization (ROP) of a cyclic O-carboxyanhydride resulted in atactic poly(mandelic acid) (PMA), however, a well-defined pyridine/mandelic acid adduct enabled excellent control over the ROP, providing highly isotactic chiral PMA with an enhanced heat resistance. Tg=glass-transition temperature.

Angew. Chem. Int. Ed., October 14, 2014, DOI: 10.1002/anie.201407525

Hydroxyl-Functionalized Imidazoles: Highly Active Additives for the Potassium Iodide-Catalyzed Synthesis of 1,3-Dioxolan-2-one Derivatives from Epoxides and Carbon Dioxide

A perfect combination: The combination of commercially available 4(5)-(hydroxymethyl)imidazole (HMI) and potassium iodide serves as a simple and efficient catalyst system for the coupling reaction of epoxides with carbon dioxide. Several epoxides are converted into cyclic carbonates in high yields (up to 99 %) under mild and solvent-free conditions within a short reaction time. This new catalyst system demonstrates higher activity than the previously reported potassium iodide/triethanolamine (TEA) system.

ChemCatChem, October 10, 2014, DOI: 10.1002/cctc.201402572

Yu-Chen Zhang, Jia-Jia Zhao, Fei Jiang, Si-Bing Sun, Feng Shi
Organocatalytic Asymmetric Arylative Dearomatization of 2,3-Disubstituted Indoles Enabled by Tandem Reactions [Communication]

Organocatalytic Asymmetric Arylative Dearomatization of 2,3-Disubstituted Indoles Enabled by Tandem Reactions

Less aromatic: The title reaction between indoles and quinone imine ketals was achieved by the two tandem approaches shown in the scheme. In both cases, enantiomerically pure indole derivatives bearing an all-carbon quaternary stereogenic center were generated in high yields and excellent stereoselectivities.

Angew. Chem. Int. Ed., October 10, 2014, DOI: 10.1002/anie.201408551

Mesoporous Poly(melamine–formaldehyde): A Green and Recyclable Heterogeneous Organocatalyst for the Synthesis of Benzoxazoles and Benzothiazoles Using Dioxygen as Oxidant

Going round in heterocycles: Benzoxazole and benzothiazole derivatives are synthesized by using mesoporous poly(melamine–formaldehyde) as a green and recoverable catalyst. This heterogeneous organocatalytic method can provide a novel and efficient strategy for the synthesis of other N-heterocycles.

ChemCatChem, October 8, 2014, DOI: 10.1002/cctc.201402628

Zhichao Jin, Shaojin Chen, Yuhuang Wang, Pengcheng Zheng, Song Yang, Yonggui Robin Chi
β-Functionalization of Carboxylic Anhydrides with β-Alkyl Substituents through Carbene Organocatalysis [Communication]

β-Functionalization of Carboxylic Anhydrides with β-Alkyl Substituents through Carbene Organocatalysis

Nucleophilic carbon: NHC catalysis is used for the functionalization of carboxylic anhydrides. The β carbon acts as a nucleophilic carbon and undergoes asymmetric reactions with electrophiles. Anhydrides with challenging β-alkyl substituents work effectively.

Angew. Chem. Int. Ed., October 5, 2014, DOI: 10.1002/anie.201408604

Promising Combination for Asymmetric Organocatalysis: Brønsted Acid-Assisted Chiral Phosphoric Acid Catalysis

Hand-in-hand: Recent developments in Brønsted acid-assisted chiral phosphoric acid catalysis are discussed, which exhibit the superiority of the self-assembly and the specificity of substrate recognition.

ChemCatChem, October 2, 2014, DOI: 10.1002/cctc.201402652

Christian Brazel, Nathalie Dupré, Max Malacria, Bernold Hasenknopf, Emmanuel Lacôte, Serge Thorimbert
Intramolecular Anion Effect in Polyoxometalate-Based Organocatalysts: Reactivity Enhancement and Chirality Transfer by a Metal Oxide–Organic Cation Interaction [Communication]

Intramolecular Anion Effect in Polyoxometalate-Based Organocatalysts: Reactivity Enhancement and Chirality Transfer by a Metal Oxide–Organic Cation Interaction

A hybrid α1-Dawson polyanion bearing a lateral side chain with a 4-aminopyridine end group catalyzes the addition of indenyl allyl silanes to cinnamoyl fluorides. The chiral polyanionic framework influences the catalytic activity, the selectivity, and the stereoselectivity of the reaction (see figure).

Chem. Eur. J. 2014, 20, No. 49, 16074-16077

Kenichi Murai, Junki Nakajima, Akira Nakamura, Norimichi Hyogo, Hiromichi Fujioka
Enantioselective, Desymmetrizing, Bromolactonization Reactions of Symmetric Olefinic Dicarboxylic Acids [Full Paper]

Enantioselective, Desymmetrizing, Bromolactonization Reactions of Symmetric Olefinic Dicarboxylic Acids

Mirror mirror on the wall: We have developed an enantioselective, desymmetrizing, bromolactonization reaction of symmetric olefinic dicarboxylic acids that is promoted by a C3-symmetric trisimidazoline organocatalyst.

Chem. Asian J. 2014, 9, No. 12, 3511-3517

Daniel T. Ziegler, Lorena Riesgo, Takuya Ikeda, Yuji Fujiwara, Gregory C. Fu
Biphenyl-Derived Phosphepines as Chiral Nucleophilic Catalysts: Enantioselective [4+1] Annulations To Form Functionalized Cyclopentenes [Communication]

Biphenyl-Derived Phosphepines as Chiral Nucleophilic Catalysts: Enantioselective [4+1] Annulations To Form Functionalized Cyclopentenes

All in the family: A new family of chiral nucleophilic catalysts, biphenyl-derived phosphepines, and their use in the title reaction is reported. A range of one-carbon coupling partners can be employed to generate cyclopentenes bearing a fully substituted stereocenter. Initial mechanistic studies are described.

Angew. Chem. Int. Ed. 2014, 53, No. 48, 13183-13187

André Grossmann, Sean Bartlett, Matej Janecek, James T. Hodgkinson, David R. Spring
Diversity-Oriented Synthesis of Drug-Like Macrocyclic Scaffolds Using an Orthogonal Organo- and Metal Catalysis Strategy [Communication]

Diversity-Oriented Synthesis of Drug-Like Macrocyclic Scaffolds Using an Orthogonal Organo- and Metal Catalysis Strategy

Hand in hand: The outlined diversity-oriented synthesis of a library of macrocycles is based on the orthogonal combination of multiple diversity-generating organocatalytic steps with alkene metathesis. In total, 51 macrocyclic structures bearing 48 unique scaffolds, drug-like chemophysical properties, and natural-product-like shape diversity were synthesized in only 2 to 4 steps without the need for protecting groups.

Angew. Chem. Int. Ed. 2014, 53, No. 48, 13093-13097

Enantio- and Diastereoselective Access to Distant Stereocenters Embedded within Tetrahydroxanthenes: Utilizing ortho-Quinone Methides as Reactive Intermediates in Asymmetric Brønsted Acid Catalysis

Procedures for the Brønsted acid catalyzed asymmetric synthesis of 9-substituted tetrahydroxanthenones and 3,9-disubstituted tetrahydroxanthenone derivatives have been developed. The procedures are based on the in situ generation of ortho-quinone methides and their subsequent reaction with 1,3-dicarbonyl compounds. The reaction provides products with a high level of asymmetric induction.

Angew. Chem. Int. Ed. 2014, 53, No. 48, 13258-13263

María Sánchez-Roselló, Cristina Mulet, Marta Guerola, Carlos del Pozo, Santos Fustero
Microwave-Assisted Tandem Organocatalytic Peptide-Coupling Intramolecular aza-Michael Reaction: α,β-Unsaturated N-Acyl Pyrazoles as Michael Acceptors [Communication]

Microwave-Assisted Tandem Organocatalytic Peptide-Coupling Intramolecular aza-Michael Reaction: α,β-Unsaturated N-Acyl Pyrazoles as Michael Acceptors

The organocatalytic intramolecular aza-Michael reaction (IMAMR) with conjugated esters, elusive to date, was achieved by using N-acyl pyrazoles as ester surrogates (see scheme; DIC=diisopropyl carbodiimide, CPME=cyclopentyl methyl ether). Squaramides were the catalyst of choice, and the reaction was performed under microwave irradiation at 90 °C. Furthermore, the process could be also performed in a tandem peptide-coupling IMAMR starting from the corresponding conjugated carboxylic acid derivatives.

Chem. Eur. J. 2014, 20, No. 48, 15697-15701

Organocatalytic Asymmetric Mannich Cyclization of Hydroxylactams with Acetals: Total Syntheses of (−)-Epilupinine, (−)-Tashiromine, and (−)-Trachelanthamidine

Double bonanza: The title reaction in the presence of an imidazolidinone-based catalyst furnished N-bridgehead bicyclic alkaloids bearing [3.3.0], [3.4.0], [4.4.0], and [4.5.0] skeletons. By using this protocol, the total syntheses of (−)-epilupinine, (−)-tashiromine, and (−)-trachelanthamidine were achieved.

Angew. Chem. Int. Ed. 2014, 53, No. 48, 13196-13200

Jesús M. García, José M. Odriozola, Jesús Razkin, Irati Lapuerta, Amaiur Odriozola, Iñaki Urruzuno, Silvia Vera, Mikel Oiarbide, Claudio Palomo
Catalytic Enantioselective Quick Route to Aldol-Tethered 1,6- and 1,7-Enynes from ω-Unsaturated Aldehydes [Full Paper]

Catalytic Enantioselective Quick Route to Aldol-Tethered 1,6- and 1,7-Enynes from ω-Unsaturated Aldehydes

Ready to cyclize: Asymmetric synthesis of oxygenated 1,5- and 1,6-enynes is developed by means of an amine/Brønsted acid catalyzed direct cross-aldol reaction of unsaturated aldehydes. This reaction also works well with propargylic ketoesters yielding tertiary alcohols. Submission of the corresponding aldol adducts to standard O-silylation and subsequent Pauson–Khand conditions afforded the respective bicyclic products in good yields and stereoselectivities.

Chem. Eur. J. 2014, 20, No. 47, 15543-15554

Xiaoying Xu, Stephan M. Rummelt, Flavien L. Morel, Marco Ranocchiari, Jeroen A. van Bokhoven
Selective Catalytic Behavior of a Phosphine-Tagged Metal-Organic Framework Organocatalyst [Full Paper]

Selective Catalytic Behavior of a Phosphine-Tagged Metal-Organic Framework Organocatalyst

Selective catalysis by MOFs: Steric hindrance by a metal–organic framework (MOF) is shown to influence the outcome of a catalytic reaction by controlling the orientation of its intermediates, as demonstrated by using phosphine MOF LSK-3, which is evaluated with the aid of molecular modeling and NMR techniques and tested as a catalyst for coumarin synthesis, umpolung addition, Knoevenagel condensation, and [3+2] cycloaddition.

Chem. Eur. J. 2014, 20, No. 47, 15467-15472

Shoubhik Das, Felix D. Bobbink, Gabor Laurenczy, Paul J. Dyson
Metal-Free Catalyst for the Chemoselective Methylation of Amines Using Carbon Dioxide as a Carbon Source [Communication]

Metal-Free Catalyst for the Chemoselective Methylation of Amines Using Carbon Dioxide as a Carbon Source

The methylation of amines with CO2 as C1 source and Ph2SiH2 as reducing agent was achieved with an N-heterocyclic carbene (NHC) as the catalyst. The catalyst is tolerant toward a variety of functional groups (including esters and ethers, nitro, nitrile, and carbonyl groups, and unsaturated C-C bonds); the reaction uses commercially available reagents and can be performed on a gram scale.

Angew. Chem. Int. Ed. 2014, 53, No. 47, 12876-12879

Catalytic Asymmetric Construction of 3,3'-Spirooxindoles Fused with Seven-Membered Rings by Enantioselective Tandem Reactions

The catalytic asymmetric construction of a spirooxindole scaffold has been established by an organocatalytic three-component tandem reaction to provide structurally complex spirobenzodiazepine oxindoles with one quaternary stereogenic center (see scheme) in high yield with excellent enantioselectivity.

Chem. Eur. J. 2014, 20, No. 46, 15047-15052

Elena Arceo, Elisa Montroni, Paolo Melchiorre
Photo-Organocatalysis of Atom-Transfer Radical Additions to Alkenes [Communication]

Photo-Organocatalysis of Atom-Transfer Radical Additions to Alkenes

Light and simple: An organic molecule as simple as p-anisaldehyde can efficiently catalyze the intermolecular atom-transfer radical addition of a variety of haloalkanes onto olefins. The protocol requires irradiation from a household 23 W compact fluorescent light (CFL) bulb to proceed, and ambient temperature is sufficient to functionalize olefins in a synthetically useful fashion.

Angew. Chem. Int. Ed. 2014, 53, No. 45, 12064-12068

Akira Yoshimura, T. Nicholas Jones, Mekhman S. Yusubov, Viktor V. Zhdankin
Hypoiodite-Mediated Catalytic Cyclopropanation of Alkenes with Malononitrile [Communication]

Enguerrand Blondiaux, Jacky Pouessel, Thibault Cantat
Carbon Dioxide Reduction to Methylamines under Metal-Free Conditions [Communication]

Carbon Dioxide Reduction to Methylamines under Metal-Free Conditions

Organocatalysis: Proazaphosphatrane superbases prove to be highly active catalysts in the reductive functionalization of CO2, in the presence of hydroboranes. The new method makes possible the methylation of N-H bonds in a wide variety of amines, including secondary amines (see picture), with increased chemoselectivity.

Angew. Chem. Int. Ed. 2014, 53, No. 45, 12186-12190

María D. Díaz-de-Villegas, José A. Gálvez, Ramón Badorrey, Pilar López-Ram-de-Víu
Organocatalysis in Enantioselective α-Functionalization of 2-Cyanoacetates [Review]

Gabriel S. Scatena, Alexander F. de la Torre, Quezia B. Cass, Daniel G. Rivera, Márcio W. Paixão
Multicomponent Approach to Silica-Grafted Peptide Catalysts: A 3 D Continuous-Flow Organocatalytic System with On-line Monitoring of Conversion and Stereoselectivity [Full Paper]

Multicomponent Approach to Silica-Grafted Peptide Catalysts: A 3 D Continuous-Flow Organocatalytic System with On-line Monitoring of Conversion and Stereoselectivity

Fully automated: A 3 D continuous-flow organocatalytic system is designed with the integration of the microreactor and multidimensional chromatography technologies. This enamine catalysis platform enables the production of chiral γ-nitroaldehydes with on-line monitoring of the reaction parameters. Boc=tert-Butoxycarbonyl, dr=diastereomeric ratio.

ChemCatChem 2014, 6, No. 11, 3208-3214

High-Yielding Total Synthesis of Sexually Deceptive Chiloglottones and Antimicrobial Dialkylresorcinols through an Organocatalytic Reductive Coupling Reaction

Sexually deceptive chiloglottones, antimicrobial dialkylresorcinols, and their many analogues are synthesized in very good yields in a sequential two-pot manner by using an “organocatalytic reductive coupling reaction” as the key step.

Eur. J. Org. Chem. 2014, No. 33, 7317-7323

Applications of Carbohydrate-Based Organocatalysts in Enantioselective Synthesis

Carbohydrates, with their rigid backbones, large numbers of functional groups and high contents of chiral centres, are an appealing natural resource for the development of organocatalysts. They are becoming increasingly popular new tools for enantioselective synthesis, and this subject is reviewed for the period from 2009 to mid-2014.

Eur. J. Org. Chem. 2014, No. 33, 7291-7303

Organocatalyzed Asymmetric 1,4-Addition of Azlactones to α,β-Unsaturated Trichloromethyl Ketones: Synthesis of α,α-Disubstituted α-Amino Acid Derivatives

The first asymmetric 1,4-addition of azlactones to α,β-unsaturated trichloromethyl ketones by using cinchona alkaloid derived bifunctional thiourea catalysts is described. A series of α,α-disubstituted α-amino acid derivatives bearing a quaternary stereocenter at the α-position are obtained in high yields with excellent diastereo- and enantioselectivities (up to >20:1 dr and 99 % ee).

Eur. J. Org. Chem. 2014, No. 32, 7104-7108

Pedro C. Barrulas, Andrea Genoni, Maurizio Benaglia, Anthony J. Burke
Cinchona-Derived Picolinamides: Effective Organocatalysts for Stereoselective Imine Hydrosilylation [Short Communication]

Cinchona-Derived Picolinamides: Effective Organocatalysts for Stereoselective Imine Hydrosilylation

Cinchona derivatives for the successful enantioselective addition of trichlorosilane to ketimines are developed. Excellent yields with good to high enantioselectivities (up to 91 %) are obtained in the reduction of differently substituted substrates. Remarkably high turnover frequencies for imine hydrosilylation are observed at a catalyst loading of only 1 mol-%.

Eur. J. Org. Chem. 2014, No. 33, 7339-7342

Thomas Werner, Marcel Hoffmann, Sunetra Deshmukh
First Microwave-Assisted Catalytic Wittig Reaction [Short Communication]

First Microwave-Assisted Catalytic Wittig Reaction

The first catalytic Wittig reaction under microwave irradiation is reported. Readily available tributylphosphine oxide acts as the precatalyst. Under optimized conditions, a variety of aromatic, aliphatic, and heteroaromatic aldehydes could be converted efficiently. Moreover, one example of the first asymmetric version under these conditions is enclosed.

Eur. J. Org. Chem. 2014, No. 31, 6873-6876

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. 2014, 9, No. 11, 3278-3286

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. 2014, 53, No. 44, 11900-11906

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. 2014, 53, No. 44, 11849-11853

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. 2014, 53, No. 43, 11660-11664

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. 2014, 53, No. 43, 11611-11615

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. 2014, 53, No. 42, 11329-11332

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. 2014, 53, No. 42, 11194-11198

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]

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. 2014, 20, No. 42, 13811-13814

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. 2014, 53, No. 41, 10861-10863

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. 2014, No. 28, 6141-6144

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

Francesco Secci, Angelo Frongia, Maria Grazia Rubanu, Maria Laura Sechi, Giorgia Sarais, Massimiliano Arca, Pier Paolo Piras
From (Phenylsulfanyl)cycloalkanecarbaldehydes to Optically Active Spirocyclic Tetrahydrofurans: Stereospecific Resolution of Symmetric Aldehydes through (S)-Proline-Catalysed Aldol Reaction [Full Paper]

From (Phenylsulfanyl)cycloalkanecarbaldehydes to Optically Active Spirocyclic Tetrahydrofurans: Stereospecific Resolution of Symmetric Aldehydes through (S)-Proline-Catalysed Aldol Reaction

(E/Z)-(Phenylsulfanyl)cycloalkanecarbaldehydes have been stereospecifically resolved through an enantioselective (S)-proline aldol reaction with ketones. (Z)-Aldehydes furnished the corresponding aldol adducts in good yields and excellent er (98:2 to >99:1). Further reduction of the aldol adducts and treatment with TsOH furnished enantiomerically enriched spirocyclic tetrahydrofuran derivatives.

Eur. J. Org. Chem. 2014, No. 30, 6659-6675

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. 2014, No. 30, 6615-6620

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 2014, 6, No. 10, 2843-2846

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. 2014, No. 28, 6103-6119

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

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

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

© Wiley-VCH 2013.