The LANCA three-component reaction to highly substituted β-ketoenamides – versatile intermediates for the synthesis of functionalized pyridine, pyrimidine, oxazole and quinoxaline derivatives

• Tilman Lechel,
• Roopender Kumar,
• Mrinal K. Bera,
• Reinhold Zimmer and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2019, 15, 655–678, doi:10.3762/bjoc.15.61

• chiral compounds were converted into the corresponding pyridin-4-ol derivatives and tested as chiral ligands in asymmetric catalysis [37]. Using the N-trityl-substituted proline as carboxylic acid provided the expected β-ketoenamide KE42 in low yield and as major product we isolated compound 7 in 49

Asymmetric synthesis of a high added value chiral amine using immobilized ω-transaminases

• Antonella Petri,
• Valeria Colonna and
• Oreste Piccolo

Beilstein J. Org. Chem. 2019, 15, 60–66, doi:10.3762/bjoc.15.6

• sustainable approach to an industrial scale. Keywords: asymmetric catalysis; biotransformations; chiral amine; immobilized enzymes; ω-transaminases; Introduction Enantiomerically pure amines are important precursors to biologically active compounds with different industrial applications, including

A novel and practical asymmetric synthesis of eptazocine hydrobromide

• Ruipeng Li,
• Zhenren Liu,
• Liang Chen,
• Jing Pan,
• Kuaile Lin and
• Weicheng Zhou

Beilstein J. Org. Chem. 2018, 14, 2340–2347, doi:10.3762/bjoc.14.209

• were optimized to obtain the product in excellent overall yield and purity. Keywords: alkylation; asymmetric catalysis; eptazocine; Mannich cyclization; Introduction Eptazocine hydrobromide (1, Scheme 1), (1S,6S)-1,4-dimethyl-2,3,4,5,6,7-hexahydro-1H-1,6-methanobenzo[e]azonine-10-ol hydrobromide

• and methallyl iodide [10]. However, these methods were undermined by expensive reagents, poor yields, harsh reaction conditions, or complex synthetic procedures. Phase-transfer asymmetric catalysis using cinchona alkaloid-derived quaternary ammonium salts is a practical method in organic synthesis [11

D-Fructose-based spiro-fused PHOX ligands: synthesis and application in enantioselective allylic alkylation

• Michael R. Imrich,
• Jochen Kraft,
• Cäcilia Maichle-Mössmer and
• Thomas Ziegler

Beilstein J. Org. Chem. 2018, 14, 2082–2089, doi:10.3762/bjoc.14.182

• .14.182 Abstract Phosphinooxazoline (PHOX) ligands are an important class of ligands in asymmetric catalysis. We synthesized ten novel D-fructose-derived spiro-fused PHOX ligands with different steric and electronic demand. The application of two of them was tested in asymmetric allylic alkylation. The

• strongly decreased with longer reaction times (see Supporting Information File 1 for details). With the fructose-based spiro-fused PHOX ligands in hand, we turned to some preliminary tests in order to evaluate the usefulness of our ligands in asymmetric catalysis. We chose to test one ligand with ether

• lead to the highest er in our preliminary tests. The reason for this will to be studied in further investigations, as well as the application of other spiro-fused PHOX ligands in asymmetric catalysis. Conclusion In conclusion, we developed a short and efficient synthesis for D-fructose-based spiro

Synthesis and supramolecular self-assembly of glutamic acid-based squaramides

• Juan V. Alegre-Requena,
• Marleen Häring,
• Isaac G. Sonsona,
• Alex Abramov,
• Eugenia Marqués-López,
• Raquel P. Herrera and
• David Díaz Díaz

Beilstein J. Org. Chem. 2018, 14, 2065–2073, doi:10.3762/bjoc.14.180

• asymmetric catalysis and molecular recognition [5][6]. Besides, squaramides present a dual ability to recognize anions and cations through hydrogen bonding interactions, acting as ion sensors and transmembrane anion transporters [7]. This property has been crucial for the development of new drugs [8][9

Chiral bisoxazoline ligands designed to stabilize bimetallic complexes

• Deepankar Das,
• Rudrajit Mal,
• Nisha Mittal,
• Zhengbo Zhu,
• Thomas J. Emge and
• Daniel Seidel

Beilstein J. Org. Chem. 2018, 14, 2002–2011, doi:10.3762/bjoc.14.175

• pyridazine-bridged, and bis-nickel as well as bis-palladium pyrazole-bridged complexes were obtained. Keywords: bimetallic complexes; bisoxazolines; chiral ligands; heterocycles; Introduction Metal-centered asymmetric catalysis most commonly relies on monometallic complexes of various chiral ligands, among

• monooxygenase [10], ribonucleotide reductase [11], catechol oxidase [12], and arginase [13], are prominent examples of such bimetallic enzymes. A range of bi- and multi-metallic complexes have been utilized in asymmetric catalysis (Figure 1) [6]. For instance, Shibasaki and co-workers introduced a number of

• the development of new catalytic enantioselective transformations. Examples of chiral bimetallic complexes utilized in asymmetric catalysis. Previously reported bisoxazoline ligands capable of stabilizing bimetallic complexes. Thermal ellipsoid plot (50% probability) of the molecular structure of 16

Asymmetric Michael addition reactions catalyzed by calix[4]thiourea cyclohexanediamine derivatives

• Zheng-Yi Li,
• Hong-Xiao Tong,
• Yuan Chen,
• Hong-Kui Su,
• Tangxin Xiao,
• Xiao-Qiang Sun and
• Leyong Wang

Beilstein J. Org. Chem. 2018, 14, 1901–1907, doi:10.3762/bjoc.14.164

• reactions in aqueous solution with excellent enantioselectivity [35]. As part of our ongoing studies to develop novel types of organocatalysts for asymmetric catalysis, in this study, we aimed to synthesize novel upper rim-functionalized calix[4]thiourea cyclohexanediamine derivatives to catalyze asymmetric

Recent advances in hypervalent iodine(III)-catalyzed functionalization of alkenes

• Xiang Li,
• Pinhong Chen and
• Guosheng Liu

Beilstein J. Org. Chem. 2018, 14, 1813–1825, doi:10.3762/bjoc.14.154

• hypervalent iodine(III)-catalyzed functionalization of alkenes and asymmetric reactions using a chiral iodoarene are summarized. Keywords: asymmetric catalysis; functionalization of alkenes; hypervalent iodine(III); Introduction Hypervalent iodine(III) reagents, also named as λ3-iodanes, have been widely

Enantioselective phase-transfer catalyzed alkylation of 1-methyl-7-methoxy-2-tetralone: an effective route to dezocine

• Ruipeng Li,
• Zhenren Liu,
• Liang Chen,
• Jing Pan and
• Weicheng Zhou

Beilstein J. Org. Chem. 2018, 14, 1421–1427, doi:10.3762/bjoc.14.119

• -dibromopentane, and the best catalyst (C7) was identified. In addition, optimizations of the alkylation were carried out so that the process became practical and effective. Keywords: alkylation; asymmetric catalysis; cinchonidine; dezocine; Introduction The preparation of enantiomerically pure compounds has

• become a stringent requirement for pharmaceutical synthesis [1]. In this context, asymmetric catalysis is probably one of the most attractive procedures for the synthesis of active pharmaceutical ingredients (APIs) due to environmental, operational, and economic benefits. Dezocine, (5R,11S,13S)-13-amino

• separated by two times of resolution with L-tartaric acid and D-tartaric acid (Scheme 1). Phase-transfer asymmetric catalysis with cinchona alkaloid-derived quaternary ammonium compounds has become one of the topics in stereoselective synthesis in both industry and academia [6][7][8][9]. It was reported [10

Recent applications of chiral calixarenes in asymmetric catalysis

• Mustafa Durmaz,
• Erkan Halay and
• Selahattin Bozkurt

Beilstein J. Org. Chem. 2018, 14, 1389–1412, doi:10.3762/bjoc.14.117

• Analysis Technological Application and Research Center (UBATAM), Usak University, Usak, Turkey Vocational School of Health Services, Usak University, 64200 Usak, Turkey 10.3762/bjoc.14.117 Abstract The use of calixarenes in asymmetric catalysis is receiving increasing attention due to their tunable three

• -dimensional molecular platforms along with their easy syntheses and versatile modification at the upper and lower rims. This review summarizes the recent progress of synthesis and use of chiral calixarenes in asymmetric syntheses which emerged later than 2010. Keywords: asymmetric catalysis; chiral

• asymmetric catalysis has received considerable interest and witnessed significant progress in recent years [2][3][4]. Calixarenes are considered as the third generation of supramolecular hosts after cyclodextrins and crown ethers [5][6]. Due to their easy preparation and readily modification at either the

A survey of chiral hypervalent iodine reagents in asymmetric synthesis

• Soumen Ghosh,
• Suman Pradhan and
• Indranil Chatterjee

Beilstein J. Org. Chem. 2018, 14, 1244–1262, doi:10.3762/bjoc.14.107

• of an external oxidant. The use of catalytic chiral hypervalent iodine reagents in asymmetric catalysis is one of the most challenging ongoing topics and this review will focus on the development of various chiral hypervalent iodine reagents and their application in typical organic transformations

An overview of recent advances in duplex DNA recognition by small molecules

• Sayantan Bhaduri,
• Nihar Ranjan and
• Dev P. Arya

Beilstein J. Org. Chem. 2018, 14, 1051–1086, doi:10.3762/bjoc.14.93

• -based asymmetric catalysis by synthesizing various structural analogs of Hoechst 33258. It has been observed that amine analogs (conjugate 53 and 54) showed higher affinity towards ct-DNA and poly[d(A·T)2] in comparison to alkyne analogs with reduced flexibility and one less charged nitrogen atom

Nanoreactors for green catalysis

• M. Teresa De Martino,
• Loai K. E. A. Abdelmohsen,
• Floris P. J. T. Rutjes and
• Jan C. M. van Hest

Beilstein J. Org. Chem. 2018, 14, 716–733, doi:10.3762/bjoc.14.61

• and, thereby, harness its utility for further applications. The abovementioned issues are particularly relevant in the field of asymmetric catalysis, which besides overcoming catalyst compatibility also has to deal with cost issues [11][12]. Research on asymmetric catalysis has been mainly focused on

Investigations towards the stereoselective organocatalyzed Michael addition of dimethyl malonate to a racemic nitroalkene: possible route to the 4-methylpregabalin core structure

• Denisa Vargová,
• Rastislav Baran and
• Radovan Šebesta

Beilstein J. Org. Chem. 2018, 14, 553–559, doi:10.3762/bjoc.14.42

• based on chiral phase-transfer-catalysis of the Michael addition was also reported [26]. In this context, we decided to develop a synthesis of 4-methylpregabalin from a simple and achiral starting material and build its chirality centers using asymmetric catalysis. This paper describes the synthesis of

Recent developments in the asymmetric Reformatsky-type reaction

• Hélène Pellissier

Beilstein J. Org. Chem. 2018, 14, 325–344, doi:10.3762/bjoc.14.21

• benzoxathiazine 2,2-dioxides, as electrophiles in the catalytic enantioselective aza-Reformatky reaction [49]. Indeed, these compounds constitute good partners for asymmetric catalysis since they exhibit a rigid structure reducing the conformational mobility and avoiding the E/Z isomerization, thus facilitating

Photocatalytic formation of carbon–sulfur bonds

• Alexander Wimmer and
• Burkhard König

Beilstein J. Org. Chem. 2018, 14, 54–83, doi:10.3762/bjoc.14.4

• substances used in material synthesis bear sulfur-containing functional groups. Furthermore, the unique chemical properties of sulfur find applications in asymmetric catalysis or material design [14][15][16][17][18][19]. Therefore, many well established and highly efficient strategies for the formation of C

Exploring mechanochemistry to turn organic bio-relevant molecules into metal-organic frameworks: a short review

• Vânia André,
• Sílvia Quaresma,
• João Luís Ferreira da Silva and
• M. Teresa Duarte

Beilstein J. Org. Chem. 2017, 13, 2416–2427, doi:10.3762/bjoc.13.239

• and materials sciences, including organic solids [2] with pharmaceutical, luminescence- and thermoactive properties; studies of biomolecular recognition, asymmetric catalysis, interlocked systems and racemic resolution [2]. More recently mechanochemical methods were again successfully applied to the

Conjugated nitrosoalkenes as Michael acceptors in carbon–carbon bond forming reactions: a review and perspective

• Yaroslav D. Boyko,
• Valentin S. Dorokhov,
• Alexey Yu. Sukhorukov and
• Sema L. Ioffe

Beilstein J. Org. Chem. 2017, 13, 2214–2234, doi:10.3762/bjoc.13.220

• nucleophile as well as asymmetric catalysis still remains to be studied in these reactions. The high efficiency and stereoselectivity of the enolate addition to nitrosoalkenes make this strategy perspective for application in total synthesis that has been recognized since 1970s. Thus, Oppolzer and co-workers

Chiral phase-transfer catalysis in the asymmetric α-heterofunctionalization of prochiral nucleophiles

• Johannes Schörgenhumer,
• Maximilian Tiffner and
• Mario Waser

Beilstein J. Org. Chem. 2017, 13, 1753–1769, doi:10.3762/bjoc.13.170

• Johannes Schorgenhumer Maximilian Tiffner Mario Waser Institute of Organic Chemistry, Johannes Kepler University Linz, Altenbergerstrasse 69, 4040 Linz, Austria 10.3762/bjoc.13.170 Abstract Chiral phase-transfer catalysis is one of the major catalytic principles in asymmetric catalysis. A broad

• a variety of highly versatile methods for asymmetric catalysis [24][55][56][57][58][59][60][61][62][63]. In contrast to chiral cation-based PTCs, which mainly operate through coordination and control of the nucleophile, these anionic PTCs usually coordinate cationic (and often hardly soluble

• -chlorination of β-ketoesters 1, by using N-chlorosuccinimide (14) as the Cl-transfer agent [76]. In continuation of our efforts to develop bifunctional ammonium salts D for asymmetric catalysis we have also recently investigated the asymmetric synthesis of α-chloroketoesters 12 [92]. We found that catalyst

Construction of highly enantioenriched spirocyclopentaneoxindoles containing four consecutive stereocenters via thiourea-catalyzed asymmetric Michael–Henry cascade reactions

• Yonglei Du,
• Jian Li,
• Kerong Chen,
• Chenglin Wu,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2017, 13, 1342–1349, doi:10.3762/bjoc.13.131

• spirocyclopentaneoxindoles containing multiple contiguous stereocenters remains challenging [23][24][25][26]. The medicinal properties of these frameworks mean that fast enrichment of spirooxindoles bearing diverse functional groups is of considerable importance. Recently, an increasing number of asymmetric catalysis

Strategies in asymmetric catalysis

• Tehshik P. Yoon

Beilstein J. Org. Chem. 2017, 13, 63–64, doi:10.3762/bjoc.13.8

• Tehshik P. Yoon Department of Chemistry, University of Wisconsin–Madison, 1101 University Avenue, Madison, WI 53706, USA 10.3762/bjoc.13.8 Keywords: asymmetric catalysis; enantioselectivity; stereoselectivity; The stereochemistry of an organic compound can have a profound influence on many of

• reactions. Those of us with research interests in stereoselective synthesis lauded this award because it celebrated the creative insights of these pioneers in asymmetric catalysis and because it marked a general recognition that enantioselective catalysis has had a significant practical impact on the

• of asymmetric catalytic systems remains an active and vital research area. Current progress in the field of asymmetric catalysis continues to be driven both by conceptual innovations as well as demonstrations of the applicability of enantioselective catalytic reactions to increasingly complex

New approaches to organocatalysis based on C–H and C–X bonding for electrophilic substrate activation

• Pavel Nagorny and
• Zhankui Sun

Beilstein J. Org. Chem. 2016, 12, 2834–2848, doi:10.3762/bjoc.12.283

• and are critical for the resolution. This example clearly demonstrate the great potential of halogen bonds as tools for asymmetric catalysis. Early uses of halogen bond donors in catalysis and organocatalysis Like hydrogen bonds, halogen bonds possess important features such as strength and

Chromium(II)-catalyzed enantioselective arylation of ketones

• Gang Wang,
• Shutao Sun,
• Ying Mao,
• Zhiyu Xie and
• Lei Liu

Beilstein J. Org. Chem. 2016, 12, 2771–2775, doi:10.3762/bjoc.12.275

• ; asymmetric catalysis; chromium; ketone; tertiary alcohol; Introduction Catalytic enantioselective carbon–carbon bond formation reactions have achieved enormous development during the last few decades as a consequence of the growing demand for enantiopure compounds in modern industry, especially the

Green chemistry

• Luigi Vaccaro

Beilstein J. Org. Chem. 2016, 12, 2763–2765, doi:10.3762/bjoc.12.273

• , including “Strategies in asymmetric catalysis” by Tehshik P. Yoon [6], “Organometallic chemistry” by Bernd F. Straub and Lutz H. Gade [7], “C–H functionalization/activation in organic synthesis” by Richmond Sarpong [8], “Bifunctional catalysis” by Darren J. Dixon [9], “Sustainable catalysis” by Nicholas J

Experimental and theoretical investigations into the stability of cyclic aminals

• Edgar Sawatzky,
• Antonios Drakopoulos,
• Martin Rölz,
• Christoph Sotriffer,
• Bernd Engels and
• Michael Decker

Beilstein J. Org. Chem. 2016, 12, 2280–2292, doi:10.3762/bjoc.12.221

• Tetraponera sp. [1][2]. It is also present in ligands of ruthenium-based catalysts for metathesis [3], in imidazolidines acting as antiprotozoal and antibacterial agents [4][5], in Tröger’s base derivatives with diverse applications [6][7][8][9][10][11][12][13][14] (e.g., asymmetric catalysis, supramolecular