News from European Journal of Organic Chemistry

EurBest in EurJOC: Tandem Aldol Condensation/Platinacycle-Catalyzed Addition Reactions of Aldehydes, Methyl Ketones, and Arylboronic Acids

2012-10-19T00:00:00+02:00

The aldol condensation of aldehydes with methyl ketones was successfully combined with the platinacycle-catalyzed addition reactions of arylboronic acids in a tandem fashion. A variety of β-arylated ketones was obtained in good to excellent yields.

Yuan-Xi Liao and Qiao-Sheng Hu
DOI: 10.1002/ejoc.201200867

EurBest in EurJOC: Potassium 4-Iodylbenzenesulfonate: Preparation, Structure, and Application as a Reagent for Oxidative Iodination of Arenes

2012-10-19T00:10:00+02:00

A new hypervalent iodine(V) compound, potassium 4-iodylbenzenesulfonate, was prepared by oxidation of 4-iodobenzenesulfonic acid with Oxone in water. This new reagent promises many practical applications as a thermally stable, water-soluble and recyclable hypervalent iodine oxidant, particularly useful for oxidative iodination of aromatic substrates.

Mekhman S. Yusubov, Roza Y. Yusubova, Victor N. Nemykin, Andrey V. Maskaev, Margarita R. Geraskina, Andreas Kirschning and Viktor V. Zhdankin
DOI: 10.1002/ejoc.201201064

EurBest in EurJOC: On the Reactivity and Selectivity of Galacturonic Acid Lactones

2012-10-10T00:00:00+02:00

The reactivity and stereoselectivity of a galacturonic acid 3,6-lactone thioglycosyl donor has been investigated by using thiophilic activator systems. The reactivity of the thioglycosides depends on the activator system used. The stereoselectivity arises from preactivation of the glycosylation system, giving rise to α-selective glycosylation, whereas in situ activation gives the β-product.

Alphert E. Christina, Joey A. Muns, Jeremy Q. A. Olivier, Lotte Visser, Bas Hagen, Leendert J. van den Bos, Herman S. Overkleeft, Jeroen D. C. Codée and Gijs A. van der Marel
DOI: 10.1002/ejoc.201200717

EurBest in EurJOC: Phosphane-Catalyzed [4+2] Annulation of Allenoates with Ketimines: Synthesis of Sultam-Fused Tetrahydropyridines

2012-10-10T00:10:00+02:00

Cyclic ketimines were successfully used as electrophiles in phosphane-catalyzed [4+2] annulation reactions with ethyl 2-methyl-2,3-butadienoate to give the corresponding highly substituted tetrahydropyridine derivatives in moderate to good yields (5573 %), and with moderate to excellent regioselectivity.

Xiang-Yu Chen and Song Ye
DOI: 10.1002/ejoc.201200747

EurBest in EurJOC: Lyngbyabellins K–N from Two Palmyra Atoll Collections of the Marine Cyanobacterium Moorea bouillonii

2012-09-18T00:00:00+02:00

Two independent collections of the marine cyanobacterium Moorea bouillonii led to the isolation of five lipopeptides of the lyngbyabellin structure class. Their structures were elucidated by various spectroscopy, synthesis, and chromatography techniques. Lyngbyabellin N showed strong cytotoxic activity against the HCT116 colon cancer cell line (IC₅₀ = 40.9 ± 3.3 nM).

Hyukjae Choi, Emily Mevers, Tara Byrum, Frederick A. Valeriote and William H. Gerwick
DOI: 10.1002/ejoc.201200691

EurBest in EurJOC: Arylamine-Modified Thiazoles as Donor–Acceptor Dyes: Quantum Chemical Evaluation of the Charge-Transfer Process and Testing as Ligands in Ruthenium(II) Complexes

2012-09-17T00:00:00+02:00

Several 4-hydroxy-1,3-thiazole-based chromophores bearing different arylamine donor and N-heterocyclic acceptor moieties were synthesized and their electronic properties were investigated experimentally and theoretically (DFT and TDDFT). The nature of the charge-transfer transition was identified. Additionally, the dyes were applied as light-harvesting ligands in heteroleptic Ru^II complexes.

Roberto Menzel, Stephan Kupfer, Ralf Mede, Dieter Weiß, Helmar Görls, Leticia González and Rainer Beckert
DOI: 10.1002/ejoc.201200688

EurBest in EurJOC: General and Efficient α-Oxygenation of Carbonyl Compounds by TEMPO Induced by Single-Electron-Transfer Oxidation of Their Enolates

2012-09-11T00:00:00+02:00

The oxygenation of enolates proves to be the most general and effective methodology for the synthesis of O-protected α-oxy carbonyl compounds and nitriles A. The scope and limitations of the electron-transfer-induced radical coupling reaction with TEMPO are presented. The reaction pathways are outlined. Methods for the deprotection to α-hydroxy carbonyl compounds B are provided and discussed.

Emanuela Dinca, Philip Hartmann, Jakub Smrček, Ina Dix, Peter G. Jones and Ullrich Jahn
DOI: 10.1002/ejoc.201200736

EurBest in EurJOC: Blurring the Boundary between Bio- and Geohopanoids: Plakohopanoid, a C32 Biohopanoid Ester from Plakortis cf. lita

2012-09-11T00:10:00+02:00

Plakohopanoid is a new type of hopanoid composed of a C₃₂ hopanoic acid ester linked to a mannosyl-myo-inositol. It is probably produced by bacterial symbionts of Plakortis cf. lita. The existence of a biosynthetic pathway to the C₃₂ hopanoic acid shows that this compound should not be necessarily considered to be a geohopanoid.

Valeria Costantino, Gerardo Della Sala, Alfonso Mangoni, Cristina Perinu and Roberta Teta
DOI: 10.1002/ejoc.201200676

EurBest in EurJOC: Special Electronic Structure and Extended Supramolecular Oligomerization of Anionic 1,4-Dicorannulenylbenzene

2012-09-05T00:00:00+02:00

The reduction of 1,4-dicorannulenylbenzene is strongly affected by the benzene spacer, yielding an unexpected triplet ground state of the dianion and an octaanion that self-assembles into highly charged supramolecular oligomers that are longer than previously observed dicorannulenyl oligomers.

David Eisenberg, Jennifer M. Quimby, Derrick Ho, Ronit Lavi, Laurent Benisvy, Lawrence T. Scott and Roy Shenhar
DOI: 10.1002/ejoc.201200714

EurBest in EurJOC: Sesquiterpenoids from Common Ragweed (Ambrosia artemisiifolia L.), an Invasive Biological Polluter

2012-09-04T00:00:00+02:00

Eight novel sesquiterpenoids were isolated from the aerial parts of Ambrosia artemisiifolia, an invasive weed whose pollen is responsible for severe allergic reactions. α,β-Unsaturated carbonyl derivatives were present in all aerial parts of the plant, and their reaction with thiols was correlated with the activation of TRPA1, a polymodal sensor involved in airways sensory irritation.

Orazio Taglialatela-Scafati, Federica Pollastro, Alberto Minassi, Giuseppina Chianese, Luciano De Petrocellis, Vincenzo Di Marzo and Giovanni Appendino
DOI: 10.1002/ejoc.201200650

EurBest in EurJOC: Controllable Regioselective Construction of Both Functional α-Methylene-β- and -γ-amino Acid Derivatives Through an Organocatalyzed Tandem Allylic Alkylation and Amination

2012-08-29T00:00:00+02:00

A controllable regioselective allylic alkylation and amination reaction has been developed by using α-amino nitriles for the highly selective construction of β- and γ-amino acid derivatives incorporating multiple functional groups. Subsequent multicomponent tandem reactions and transformations of the densely functionalized products were shown to readily afford a range of useful building blocks.

Feng Pan, Jian-Ming Chen, Tian-You Qin, Sean Xiao-An Zhang and Wei-Wei Liao
DOI: 10.1002/ejoc.201200642

EurBest in EurJOC: Synthesis of SHIP1-Activating Analogs of the Sponge Meroterpenoid Pelorol

2012-08-21T00:00:00+02:00

Two biomimetic routes have been used to synthesize analogs of the SHIP1-activating sponge meroterpenoid pelorol (1) in high ee. Resorcinol analog 18 is the most effective SHIP1-activating pelorol analog made to date and racemic 28•HCl, an amino analog, activates SHIP1 in vitro, and has effective antiinflammatory activity in a mouse model (ED₅₀ ≈ 0.1 mg/kg).

Labros G. Meimetis, Matt Nodwell, Lu Yang, Xiaoxia Wang, Joyce Wu, Curtis Harwig, Grant R. Stenton, Lloyd F. Mackenzie, Thomas MacRury, Brian O. Patrick, Andrew Ming-Lum, Christopher J. Ong, Gerald Krystal, Alice L.-F. Mui and Raymond J. Andersen
DOI: 10.1002/ejoc.201200631

EurBest in EurJOC: The Δ2,2'-Bi(2H-1,4-benzothiazine) Structural Motif of Red Hair Pigments Revisited: Photochromism and Acidichromism in a Unique Four-State System

2012-08-14T00:00:00+02:00

The stable yellow form of Δ^2,2'-bi(2H-1,4-benzothiazine) (BBTZ) is shown to be the Z rather than E isomer, as originally suggested. The latter configuration pertains to the red photoexcited form. A blue species produced by diprotonation of BBTZ in 2 M HCl is also disclosed. BBTZ is thus proposed as a robust bioinspired four-state chromic system.

Loredana Leone, Orlando Crescenzi, Alessandra Napolitano, Vincenzo Barone and Marco d'Ischia
DOI: 10.1002/ejoc.201200673

EurBest in EurJOC: Mori–Hiyama versus Hay Coupling for Higher Polyynes

2012-08-07T00:00:00+02:00

A series of diaryloctatetraynes was synthesized by MoriHiyama and Hay protocols. Target compounds were isolated and spectroscopically characterized. Crystalline samples were analyzed by X-ray diffraction methods and the structures were closely scrutinized to reveal potential for topochemical 1,n-polymerization.

Nurbey Gulia, Karolina Osowska, Bartłomiej Pigulski, Tadeusz Lis, Zbigniew Galewski and Sławomir Szafert
DOI: 10.1002/ejoc.201200554

EurBest in EurJOC: Synthetic Studies Towards the Core Tricyclic Ring System of Pradimicin A

2012-07-31T00:00:00+02:00

A model study towards the synthesis of the CDE tricyclic core of the carbohydrate binding agent, pradimicin A, is described. Alkoxyallylboration provided the differentially protected diol unit of the central ring. Optimization of a key enyne cycloisomerization reaction led to the synthesis of the tricycle by a one-pot Pd-catalyzed cycloisomerization/DielsAlder cycloaddition/aromatization.

Laura Zilke and Dennis G. Hall
DOI: 10.1002/ejoc.201200294

EurBest in EurJOC: A Bifunctional β-Isocupreidine Derivative as Catalyst for the Enantioselective Morita–Baylis–Hillman Reaction and a Mechanistic Rationale for Enantioselectivity

2012-07-31T00:10:00+02:00

β-Isocupreidine derivatives were used to catalyze the asymmetric MoritaBaylisHillman (MBH) reaction, giving the (R)-MBH adducts in excellent optical purities and moderate to good yields. Both 2,6-dimethyl-4-nitrophenyl and hexafluoroisopropyl acrylate could be used. The rate- and selectivity-determining step was identified and the structures of the preferred transition states were computed.

Gianluca Martelli, Mario Orena and Samuele Rinaldi
DOI: 10.1002/ejoc.201200405

EurBest in EurJOC: Total Synthesis of Potent Antitumor Macrolide (–)-Zampanolide: An Oxidative Intramolecular Cyclization-Based Strategy

2012-07-24T00:00:00+02:00

An enantioselective synthesis of ()-zampanolide has been achieved. This rare marine natural product shows microtubule-stabilizing properties. It also displays potent activity against taxol-resistant cells. This synthesis will provide a convenient access to analogues for important structureactivity relationship studies and less complex anticancer agents related to zampanolide.

Arun K. Ghosh, Xu Cheng, Ruoli Bai and Ernest Hamel
DOI: 10.1002/ejoc.201200286

EurBest in EurJOC: Synthesis of α-Amino Acids through Samarium(II) Iodide Promoted Reductive Coupling of Nitrones with CO2

2012-07-24T00:10:00+02:00

A novel approach to the synthesis of α-amino acids is disclosed, involving C-carboxylation of nitrones by gaseous CO₂ under reductive coupling reaction conditions (SmI₂, 0.1 M in THF) at ambient temperature and 50 bar of CO₂ pressure.

Alexander Prikhod'ko, Olaf Walter, Thomas A. Zevaco, Jaime Garcia-Rodriguez, Omar Mouhtady and Sandrine Py
DOI: 10.1002/ejoc.201200440

EurBest in EurJOC: Buchwald–Hartwig Amination of (Hetero)aryl Chlorides by Employing Mor-DalPhos under Aqueous and Solvent-Free Conditions

2012-07-17T00:00:00+02:00

We report on the use of [Pd(cinnamyl)Cl]₂/Mor-DalPhos in the BuchwaldHartwig amination of (hetero)aryl chlorides with primary or secondary amines under aqueous or solvent-free conditions (52examples).

Bennett J. Tardiff and Mark Stradiotto
DOI: 10.1002/ejoc.201200510

EurBest in EurJOC: Catalytic Asymmetric Addition of Alkyllithium Reagents to Aromatic Aldehydes

2012-07-17T00:10:00+02:00

Herein, we report the first efficient catalytic system for the asymmetric alkylation of aldehydes with organolithium reagents in the presence of titanium(IV) isopropoxide. A variety of alkyllithium reagents can be added to aromatic aldehydes in good yields with high enantioselectivities in a simple one-pot procedure under mild conditions.

Emilio Fernández-Mateos, Beatriz Maciá and Miguel Yus
DOI: 10.1002/ejoc.201200464

EurBest in EurJOC: Heck–Matsuda Arylation as a Strategy to Access Kavalactones Isolated from Polygala sabulosa, Piper methysticum, and Analogues

2012-07-04T00:00:00+02:00

The HeckMatsuda reaction was applied to the syntheses of three bioactive pyrones isolated from Polygala sabulosa, eight kavalactones isolated from Piper methysticum, and several kavalactone analogues.

Cristian Soldi, Angélica V. Moro, Moacir G. Pizzolatti and Carlos R. D. Correia
DOI: 10.1002/ejoc.201200308

EurBest in EurJOC: Monitoring Fluoride Binding in DMSO: Why is a Singular Binding Behavior Observed?

2012-07-04T00:10:00+02:00

The titration behavior for fluoride binding in DMSO can often not be ascribed to a classical 1:1 binding isotherm. The culprit can be water, which leads to the generation of other species that can interact with the molecular receptor. The plethora of equilibria to be considered makes the quantitative evaluation of fluoride binding extremely perilous.

Matthieu Goursaud, Paolo De Bernardin, Antonella Dalla Cort, Kristin Bartik and Gilles Bruylants
DOI: 10.1002/ejoc.201200165

EurBest in EurJOC: Reaction Mechanism of Phosphane-Catalyzed [4+2] Annulations between α-Alkylallenoates and Activated Alkenes: A Computational Study

2012-06-26T00:00:00+02:00

This DFT study reveals that the water-aided [3+2] addition and direct [4+2] addition mechanisms are both feasible for the titled [4+2] annulations. Unlike typical [3+2] annulations, which require water as hydrogen transfer mediator, [4+2] annulation can occur without additional mediator because the carbon bearing nitrile groups can act as the hydrogen transfer mediator.

Lili Zhao, Mingwei Wen and Zhi-Xiang Wang
DOI: 10.1002/ejoc.201200121

EurBest in EurJOC: A Facile, Versatile, and Mild Morita–Baylis–Hillman-Type Reaction for the Modular One-Pot Synthesis of Highly Functionalized MBH Adducts

2012-06-26T00:10:00+02:00

Here we describe a one-pot, fast, and high-yielding methodology for the synthesis of different MoritaBaylisHillman derivatives by a four-component cascade reaction. The cascade is based on a Michael/aldol/O-functionalization/selenoxide elimination sequence. This protocol completely avoids the manipulation of selenium species with an unpleasant odor.

Bruno A. Sousa and Alcindo A. Dos Santos
DOI: 10.1002/ejoc.201200371

EurBest in EurJOC: Exploring the Ribose Sub-Pocket of the Substrate-Binding Site in Escherichia coli IspE: Structure-Based Design, Synthesis, and Biological Evaluation of Cytosines and Cytosine Analogues

2012-06-19T00:00:00+02:00

We report the design, synthesis, and biological evaluation of new cytosine- and 2-aminopyridine-based ligands to explore the molecular recognition properties of the ribose sub-pocket of the substrate-binding site in the IspE protein of Escherichia coli, a model enzyme for P. falciparum IspE.

Andri P. Schütz, Sho Osawa, Jennifer Mathis, Anna K. H. Hirsch, Bruno Bernet, Boris Illarionov, Markus Fischer, Adelbert Bacher and François Diederich
DOI: 10.1002/ejoc.201200296

EurBest in EurJOC: C–C Coupling of Acyclic Nitronates with Silyl Ketene Acetals under Silyl Triflate Catalysis: Reactivity Umpolung of Aliphatic Nitro Compounds

2012-06-19T00:10:00+02:00

A very simple approach for umpolung of the conventional reactivity of nitroalkanes through their activation by silylation offers a convenient and efficient strategy for their CC coupling with π-nucleophiles. Both primary (8 examples) and secondary (4 examples) nitroalkanes may be involved in coupling with silyl ketene acetals (4 examples) to provide a concise route to substituted β-amino acids.

Khomutova, Vladimir A. Tartakovsky and Sema L. Ioffe
DOI: 10.1002/ejoc.201200239

EurBest in EurJOC: Total Syntheses of Dichotomines A–D and the Stereochemical Revision of Dichotomines B–D

2012-06-12T00:00:00+02:00

New asymmetric total syntheses of ()-dichotomines AD (14) starting from L-tryptophan methyl ester and 2,3-O-isopropylidene-D-glyceraldehyde are described. The absolute configuration of the stereogenic center of ()-dichotomine A (1) was reconfirmed as (S), whereas the absolute configurations of the stereogenic centers of ()-dichotomines BD (24) were revised as (R).

Qiang Zhang, Jing Dong, Xiao-Xin Shi and Xia Lu
DOI: 10.1002/ejoc.201200235

EurBest in EurJOC: Straightforward Synthesis of Poly(dimethylsiloxane) Phases with Immobilized (1R)-3-(Perfluoroalkanoyl)camphorate Metal Complexes and Their Application in Enantioselective Complexation Gas Chromatography

2012-06-12T00:10:00+02:00

A novel synthetic approach to camphor-based chemically bonded Chirasil-Metal-OC₃ [Ni, Eu, La, V(O)] stationary phases and their application in enantioselective complexation GC is presented. Immobilization and metal incorporation was studied with a range of selector concentrations using NMR and IR spectroscopy. Overall, 29 compounds with different functionalities were separated with α-values up to 1.66.

Markus J. Spallek, Golo Storch and Oliver Trapp
DOI: 10.1002/ejoc.201200075

EurBest in EurJOC: Matrix Isolation and Spectroscopic Characterization of 2,5,6-Trifluoropyridylnitren-3-yl

2012-06-05T00:00:00+02:00

The combination of an aryl radical with an arylnitrene results in new motives for the construction of organic high-spin molecules. Photolysis of 3-iodo-2,5,6-trifluoropyridyl azide under the conditions of matrix isolation results in the formation of a nitrene radical with a quartet ground state. The electronic structure of this nitrene radical is described best as a σ,σ,π-triradical. The nitrene radical is stable at cryogenic temperatures but, upon irradiation, rearranges to a thermodynamically more stable azirinyl radical.

Dirk Grote, Christopher Finke, Patrik Neuhaus and Wolfram Sander
DOI: 10.1002/ejoc.201101866

EurBest in EurJOC: C3v-Symmetrical Tribenzotriquinacenes Bearing Six Benzylic Tentacle Groups at the Molecular Periphery

2012-05-29T00:00:00+02:00

A new tribenzotriquinacene-based sixfold benzyl chloride bearing three n-propyl residues at the outer bridgehead positions was synthesized and found to be a versatile key intermediate for tentacular extensions of the C_3v-symmetrical TBTQ framework by using efficient multiple FriedelCrafts and etherification reactions.

Ehsan Ullah Mughal and Dietmar Kuck
DOI: 10.1002/ejoc.201200194

EurBest in EurJOC: Selective N-Alkylation of Arylamines with Alkyl Chloride in Ionic Liquids: Scope and Applications

2012-05-22T00:00:00+02:00

A protocol for the selective N-alkylation of primary aromatic amines in tetraalkylammonium ionic liquids was developed. This approach complements existing strategies by broadening the scope with more challenging substrates (e.g., p-nitroaniline) and alkylating agents (chloroalkane).

Antonio Monopoli, Pietro Cotugno, Marina Cortese, Cosima Damiana Calvano, Francesco Ciminale and Angelo Nacci
DOI: 10.1002/ejoc.201200202

EurBest in EurJOC: FeCl3•6H2O and TfOH as Catalysts for Allylic Amination Reaction: A Comparative Study

2012-05-22T00:10:00+02:00

A comparative study for the direct allylic amination employing FeCl₃6H₂O and TfOH as efficient and readily available catalysts is described. From the results of this study it can be concluded that, with some exceptions, TfOH performed better with lower catalyst loading and milder reaction conditions. The stereochemical course of the reaction is also discussed concluding that depends on the stability of the final product.

Paz Trillo, Alejandro Baeza and Carmen Nájera
DOI: 10.1002/ejoc.201101844

EurBest in EurJOC: Intramolecular Iodine-Mediated Oxygen Transfer from Nitro Groups to C≡C Bonds

2012-05-15T00:00:00+02:00

The first examples of highly regioselective iodine-mediated nitro-alkyne cycloisomerization to afford fused isoxazoles are presented.

Inga Cikotiene
DOI: 10.1002/ejoc.201200100

EurBest in EurJOC: Synthesis of Calixarene-Based Bis(iminophosphoranes) and Their Use in Suzuki–Miyaura Cross-Coupling

2012-05-15T00:10:00+02:00

Calix[4]arenes with two iminophosphorane units tethered at their upper rims have been synthesised for the first time and used in palladium-catalysed cross-couplings between phenylboronic acid and aryl halides. The good performances of the ligands possibly arise from their capacity to form chelate complexes in highly crowded metal environments.

Laure Monnereau, David Sémeril and Dominique Matt
DOI: 10.1002/ejoc.201200082

EurBest in EurJOC: Diversified Aminohydantoins from Ureas and Thioureas Tethered to Amides

2012-05-08T00:00:00+02:00

Intramolecular cyclization of thioureas or ureas tethered to amides afforded 2-iminohydantoins and 2-amino-1H-imidazol-4(5H)-ones in very high yields (87100 %) regardless of the substituent (alkyls or aryls). This reaction proceeds through carbodiimides and iminium ions as intermediates.

Sukumar Bepary, In Kwon Youn, Hee-Jong Lim and Ge Hyeong Lee
DOI: 10.1002/ejoc.201200025

EurBest in EurJOC: Three-Component Coupling of Aldehydes, Amines, and Alkynes Catalyzed by Oxidized Copper Nanoparticles on Titania

2012-04-30T00:00:00+02:00

A³ coupling catalyzed by ultrafine copper nanoparticles on titania under solvent-free conditions is described. Some examples of KA² coupling are also reported. The catalyst is reusable and exhibited better performance than commercially available copper catalysts. The participation of copper(I) acetylides in a heterogeneous process has been demonstrated.

María José Albaladejo, Francisco Alonso, Yanina Moglie and Miguel Yus
DOI: 10.1002/ejoc.201200090

EurBest in EurJOC: Hydroxythiazole-Based Fluorescent Probes for Fluoride Ion Detection

2012-04-24T00:00:00+02:00

O-Silyloxy-1,3-thiazoles are used as fast-response ''turn-on'' probes for fluoride ion detection in polar aprotic solvents and in aqueous cetyltrimethylammonium bromide micellar medium. The high selectivity, sensitivity, and detection limit (10⁷ mol L¹ in DMSO) are an advantage over other methods.

Lorena K. Calderón-Ortiz, Eric Täuscher, Erick Leite Bastos, Helmar Görls, Dieter Weiß and Rainer Beckert
DOI: 10.1002/ejoc.201200140