Analysis of sesquiterpene hydrocarbons in grape berry exocarp (Vitis vinifera L.) using in vivo-labeling and comprehensive two-dimensional gas chromatography–mass spectrometry (GC×GC–MS)

• Philipp P. Könen and
• Matthias Wüst

Beilstein J. Org. Chem. 2019, 15, 1945–1961, doi:10.3762/bjoc.15.190

• via (S)-(−)-germacrene D or (R)-(+)-germacrene D was investigated by feeding experiments using the precursor [5,5-2H2]-1-deoxy-ᴅ-xylulose (d2-DOX, Scheme 3). Indeed, in Lemberger (R)-(+)-germacrene D and (S)-(−)-germacrene D are detectable in grape berry exocarp as shown by enantioselective analysis

• (Scheme 4), which can, indeed, be detected by enantioselective GC in ripening Lemberger berries [5]. The MS spectra and the expected labeling patterns of genuine (A) and deuterium-labeled d6-α-ylangene (C) after feeding experiments with d2-DOX are shown in Figure 5. Figure 5B shows that after feeding

N-(1-Phenylethyl)aziridine-2-carboxylate esters in the synthesis of biologically relevant compounds

• Iwona E. Głowacka,
• Aleksandra Trocha,
• Andrzej E. Wróblewski and
• Dorota G. Piotrowska

Beilstein J. Org. Chem. 2019, 15, 1722–1757, doi:10.3762/bjoc.15.168

• racemization, alternative three-carbon chirons would be of great value in enantioselective syntheses of natural compounds and/or drugs. This review article summarizes applications of N-(1-phenylethyl)aziridine-2-carboxylates, -carbaldehydes and -methanols in syntheses of approved drugs and potential

• (2S,1'S)-6 correspond to (S)- or ʟ-serinal (Figure 3) [13]. Furthermore, since the aziridine ring openings can be accomplished with other nucleophiles and the reductive cleavage is also known [14][15] the aziridines 5–8 offer a plethora of opportunities for enantioselective synthesis of structurally

• nucleophiles to provide 9 or even by catalytic hydrogenation to form 10. Thus, biologically important fragments like vicinal amino alcohols 11 or 2-amino-1,3-propanediols 12a [Nu = OH] can be obtained in highly enantioselective procedures preserving the absolute configuration at C2. The latter compounds are

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

• contribution in the field of TM catalysis [88]. Vanadium in the form of vanadium oxide and complexes has been reported to participate in numerous organic reactions including aerobic oxidation [89][90]. A report of Carsten Bolm has delineated the use of vanadium complexes in enantioselective oxidation of

Enantioselective PCCP Brønsted acid-catalyzed aza-Piancatelli rearrangement

• Gabrielle R. Hammersley,
• Meghan F. Nichol,
• Helena C. Steffens,
• Jose M. Delgado,
• Gesine K. Veits and
• Javier Read de Alaniz

Beilstein J. Org. Chem. 2019, 15, 1569–1574, doi:10.3762/bjoc.15.160

• Gabrielle R. Hammersley Meghan F. Nichol Helena C. Steffens Jose M. Delgado Gesine K. Veits Javier Read de Alaniz Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93106-9510, USA 10.3762/bjoc.15.160 Abstract An enantioselective aza-Piancatelli

Enantioselective Diels–Alder reaction of anthracene by chiral tritylium catalysis

• Qichao Zhang,
• Jian Lv and
• Sanzhong Luo

Beilstein J. Org. Chem. 2019, 15, 1304–1312, doi:10.3762/bjoc.15.129

• of a highly active carbocation Lewis acid catalyst. The stereocontrol potential of the chiral tritylium ion pair was demonstrated by its application in an enantioselective Diels–Alder reaction of anthracene. Keywords: anthracene; carbocation catalysis; Diels–Alder reaction; Fe(III)-based phosphate

• , could promote the Diels–Alder reaction with anthracenes and various unsaturated carbonyl compounds under mild conditions [13]. The use of latent carbocation catalysis with TP was examined in order to achieve enantioselective control. To our delight, TP catalyzed the asymmetric reaction affording

Switchable selectivity in Pd-catalyzed [3 + 2] annulations of γ-oxy-2-cycloalkenones with 3-oxoglutarates: C–C/C–C vs C–C/O–C bond formation

• Yang Liu,
• Julie Oble and
• Giovanni Poli

Beilstein J. Org. Chem. 2019, 15, 1107–1115, doi:10.3762/bjoc.15.107

• the initial step (C-allylation) as well as to the well-defined chronology of the following steps. Further work is currently ongoing to develop enantioselective versions of these new transformations. Experimental Conditions A – [3 + 2] C–C/O–C bond-forming annulations. In a Schlenk tube, under argon

Multicomponent reactions (MCRs): a useful access to the synthesis of benzo-fused γ-lactams

• Edorta Martínez de Marigorta,
• Jesús M. de Los Santos,
• Ana M. Ochoa de Retana,
• Javier Vicario and
• Francisco Palacios

Beilstein J. Org. Chem. 2019, 15, 1065–1085, doi:10.3762/bjoc.15.104

• methods include the efficiency in saving raw materials and working time. However, there is still a need of new catalytic systems to allow the enantioselective preparation of these heterocycles by multicomponent reactions. Keywords: indolin-2-ones; isoindolinones; γ-lactams; multicomponent reactions; 2

• fibrillation. Nevertheless, the most outstanding contribution is the first enantioselective Ugi synthesis of isoindolinones 46 catalysed by a chiral phosphoric acid, reported by D.-X. Wang, M.-X. Wang, J. Zhu and co-workers (route C, Scheme 13) [92]. They obtained very good yields and remarkable enantiomeric

• the large-scale synthesis in pharmaceutical laboratories and industry. Nevertheless, among the multicomponent synthetic methods available for the preparation of isoindolinones II and 2-oxindoles III, only one is enantioselective, even though many of the reactions described in this review involve the

Catalytic asymmetric oxo-Diels–Alder reactions with chiral atropisomeric biphenyl diols

• Chi-Tung Yeung,
• Wesley Ting Kwok Chan,
• Wai-Sum Lo,
• Ga-Lai Law and
• Wing-Tak Wong

Beilstein J. Org. Chem. 2019, 15, 955–962, doi:10.3762/bjoc.15.92

• diols 3, 4 and 6 with axial chiralities controlled by their corresponding additional asymmetric carbon centers were synthesized; despite having the same biphenyl scaffold, their highly enantioselective intermediates b, d and g were obtained with different strategies: asymmetric reduction with

An efficient synthesis of the guaiane sesquiterpene (−)-isoguaiene by domino metathesis

• Yuzhou Wang,
• Ahmed F. Darweesh,
• Patrick Zimdars and
• Peter Metz

Beilstein J. Org. Chem. 2019, 15, 858–862, doi:10.3762/bjoc.15.83

• roots of Parthenium hysterophorus [5]. A recent enantioselective synthesis of (−)-isoguaiene (1) from (+)-dihydrocarvone [6] enabled an unambiguous assignment of its absolute configuration as depicted in Figure 1. Due to the structural similarity of 1 and the trisnorsesquiterpene clavukerin A (2), we

New α- and β-cyclodextrin derivatives with cinchona alkaloids used in asymmetric organocatalytic reactions

• Iveta Chena Tichá,
• Simona Hybelbauerová and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2019, 15, 830–839, doi:10.3762/bjoc.15.80

• , Czech Republic 10.3762/bjoc.15.80 Abstract The preparation of new organocatalysts for asymmetric syntheses has become a key stage of enantioselective catalysis. In particular, the development of new cyclodextrin (CD)-based organocatalysts allowed to perform enantioselective reactions in water and to

• recycle catalysts. However, only a limited number of organocatalytic moieties and functional groups have been attached to CD scaffolds so far. Cinchona alkaloids are commonly used to catalyze a wide range of enantioselective reactions. Thus, in this study, we report the preparation of new α- and β-CD

• evaluated in several enantioselective reactions, specifically in the asymmetric allylic amination (AAA), which showed a promising enantiomeric excess of up to 75% ee. Furthermore, a new disubstituted α-CD catalyst was prepared as a pure AD regioisomer and also tested in the AAA. Our results indicate that (i

Stereochemical investigations on the biosynthesis of achiral (Z)-γ-bisabolene in Cryptosporangium arvum

• Jan Rinkel and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2019, 15, 789–794, doi:10.3762/bjoc.15.75

• cyclisation mechanism [27]. The absolute configuration of the intermediates nerolidyl diphosphate and the bisabolyl cation To address this question experimentally, (R)- and (S)-NPP were synthesised following a known route for enantioselective preparation of nerolidol [28] by Sharpless epoxidation of farnesol

Diastereo- and enantioselective preparation of cyclopropanol derivatives

• Marwan Simaan and
• Ilan Marek

Beilstein J. Org. Chem. 2019, 15, 752–760, doi:10.3762/bjoc.15.71

• , followed by a subsequent trapping of the resulting cyclopropylmetal species with an electrophilic source of oxygen (oxenoid) afforded various tetrasubstituted cyclopropanol derivatives in high diastereo- and enantiomeric ratios. Similarly, the enantioselective copper-catalyzed carbomagnesiation/oxidation

• and useful entry to the synthesis of these heterosubstituted three-membered rings. Results and Discussion To reach these goals, we are describing herein the diastereo- and enantioselective carbometalation reaction of cyclopropenes to provide cyclopropylmetal species. By subsequent stereoselective

• when the same sequence of diastereoselective carbometalation/oxidation was performed on cyclopropenyl ester 1, the in situ-formed donor–acceptor cyclopropanol undergoes a selective ring-opening to provide the acyclic product possessing a quaternary carbon stereocenter [57]. As the enantioselective

A chemoenzymatic synthesis of ceramide trafficking inhibitor HPA-12

• Seema V. Kanojia,
• Sucheta Chatterjee,
• Subrata Chattopadhyay and
• Dibakar Goswami

Beilstein J. Org. Chem. 2019, 15, 490–496, doi:10.3762/bjoc.15.42

• synthesis of the title compound has been developed using an efficient and highly enantioselective lipase-catalyzed acylation in a hydrophobic ionic liquid, [bmim][PF6], followed by a diastereoselective asymmetric dihydroxylation as the key steps for incorporating the stereogenic centers. The further

• (1R,3S)-HPA-12 (2) used the chiral pool approach [15][16], crystallization-induced asymmetric transformation [17], diastereoselective reduction of γ-aryl-γ-oxo-β-amino alcohol [18], cycloaddition of oxime with alkenes [19], enantioselective carbonyl reduction followed by an organocatalyzed α-amination

• and inexpensive synthesis of HPA-12 was felt. Our own interest in developing anticancer agents also prompted us to develop a new and practical enantioselective synthesis of 2 [26][27][28][29]. To realize our objective, we paid particular attention to obtain 2 using reactions that are high-yielding and

Reusable and highly enantioselective water-soluble Ru(II)-Amm-Pheox catalyst for intramolecular cyclopropanation of diazo compounds

• Hamada S. A. Mandour,
• Yoko Nakagawa,
• Masaya Tone,
• Hayato Inoue,
• Nansalmaa Otog,
• Ikuhide Fujisawa,
• Soda Chanthamath and
• Seiji Iwasa

Beilstein J. Org. Chem. 2019, 15, 357–363, doi:10.3762/bjoc.15.31

• Hibarigaoka, Tempaku-Cho, Toyohashi 441-8580, Japan 10.3762/bjoc.15.31 Abstract A reusable and highly enantioselective catalyst for the intramolecular cyclopropanation of various diazo ester and Weinreb amide derivatives was developed. The reactions catalyzed by a water-soluble Ru(II)-Amm-Pheox catalyst

Tandem copper and photoredox catalysis in photocatalytic alkene difunctionalization reactions

• Nicholas L. Reed,
• Madeline I. Herman,
• Vladimir P. Miltchev and
• Tehshik P. Yoon

Beilstein J. Org. Chem. 2019, 15, 351–356, doi:10.3762/bjoc.15.30

• ligand sets might be required, as in enantioselective catalytic oxidation reactions or certain cross-coupling applications. We wondered, therefore, if catalytic loadings of copper(II) salts might be used in these reactions by adding a secondary terminal oxidant to turn over the intermediate copper(I

• enantioselective by utilizing chiral Cu(II) complexes have thus far not been successful. A screen of several classes of privileged ligands for asymmetric copper catalysis produced only racemic oxyamination products. We interpret this observation as an indication that Cu(II) is unable to control the stereochemistry

• secondary terminal oxidant, and that Ag(I) salts appear to be uniquely effective in this capacity. This work thus provides a platform for the development of enantioselective photocatalytic alkene difunctionalization reactions that can use a chiral Cu(II) complex as a substoichiometric catalyst rather than

Oxidative radical ring-opening/cyclization of cyclopropane derivatives

• Yu Liu,
• Qiao-Lin Wang,
• Zan Chen,
• Cong-Shan Zhou,
• Bi-Quan Xiong,
• Pan-Liang Zhang,
• Chang-An Yang and
• Quan Zhou

Beilstein J. Org. Chem. 2019, 15, 256–278, doi:10.3762/bjoc.15.23

• aerobic oxidation of easily available cyclopropanols 91 via intermediate formation of peroxyketone intermediates 145, followed by enantioselective epoxide formation in the presence of a poly-L-leucine catalyst and DBU (Scheme 40) [120]. In 2014, a practical method for the conversion of 1,2-disubstituted

Synthesis of nonracemic hydroxyglutamic acids

• Dorota G. Piotrowska,
• Iwona E. Głowacka,
• Andrzej E. Wróblewski and
• Liwia Lubowiecka

Beilstein J. Org. Chem. 2019, 15, 236–255, doi:10.3762/bjoc.15.22

• (2S,3R,4S)-4 and (2R,3R,4S)-4. To secure the (3R,4R) and (3S,4S) configurations in 3,4-hydroxyglutamic acids enantioselective reduction of the carbonyl group of the cyclic imide (3R*,4S*)-110 prepared from meso-tartaric acid [108] needs to be elaborated (Scheme 27) [109]. Low temperature reduction of

• pyrrolidine-2-one (3S,4S,5R)-123 [111]. Oxidation of the hydroxymethyl group and acid hydrolysis gave (2S,3S,4S)-4 [112]. By enantioselective conjugate addition and asymmetric dihydroxylation An orthogonally protected 3,4-dihydroxy-L-glutamic acid was envisioned as an intermediate in the projected synthesis

• ; j) 6 M HCl, 80 °C. Synthesis of (2S,3S,4R)-127 by enantioselective conjugate addition and asymmetric dihydroxylation. Reagents and conditions: a) ethyl 1-phenylselenylacrylate, chiral PTC, 50% KOH, CH2Cl2; b) 1 M HCl, THF; c) 9-bromo-9-phenylfluorene, K2PO4, PbNO2, MeCN; d) NaIO4, NaHCO3, MeOH/H2O

Ruthenium-based olefin metathesis catalysts with monodentate unsymmetrical NHC ligands

• Veronica Paradiso,
• Chiara Costabile and
• Fabia Grisi

Beilstein J. Org. Chem. 2018, 14, 3122–3149, doi:10.3762/bjoc.14.292

• to 19b, resulting in 90% conversion within 3 hours [17]. No relevant differences in the catalyst reactivity were observed for the CM of 13 and 14 (Scheme 4). As a novel application of N-aryl, N’-aryl unsymmetrical ruthenium complexes in enantioselective catalysis, Grela and Schmidt very recently

Some mechanistic aspects regarding the Suzuki–Miyaura reaction between selected ortho-substituted phenylboronic acids and 3,4,5-tribromo-2,6-dimethylpyridine

• Piotr Pomarański,
• Piotr Roszkowski,
• Jan K. Maurin,
• Armand Budzianowski and
• Zbigniew Czarnocki

Beilstein J. Org. Chem. 2018, 14, 2384–2393, doi:10.3762/bjoc.14.214

• entails a direct, atropselective aryl–aryl bond formation step under asymmetric induction provided by internal or external factors. Also, the optical activation in the synthesis of biaryls may involve the separation of diastereomeric derivatives, or more elegantly, may be done by enantioselective

Practical tetrafluoroethylene fragment installation through a coupling reaction of (1,1,2,2-tetrafluorobut-3-en-1-yl)zinc bromide with various electrophiles

• Ken Tamamoto,
• Shigeyuki Yamada and
• Tsutomu Konno

Beilstein J. Org. Chem. 2018, 14, 2375–2383, doi:10.3762/bjoc.14.213

• ][6]. Notably, organofluorine compounds bearing a tetrafluoroethylene (–CF2CF2–) unit have attracted significant interest as a promising framework for various functional molecules. In the medicinal field, for example, Linclau and co-workers reported the first enantioselective synthesis and the

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

• in the presence of catalyst PTC (3). The designed synthesis is shown in Scheme 3. Two key reactions are included in this novel strategy: 1. the enantioselective alkylation of 1-methyl-7-methoxy-2-tetralone (2) with chloroacetonitrile generate 4 through the use of a phase-transfer catalyst; and 2. the

• acetic acid gave compound 8 in 83% yield. Eventually, target compound 1 was obtained from 8 via demethylation with 48% aqueous HBr solution. Conclusion In summary, we developed a new and efficient synthesis of eptazocine hydrobromide involving enantioselective phase-transfer catalyzed alkylation of 1

Stereoselective total synthesis and structural revision of the diacetylenic diol natural products strongylodiols H and I

• Pamarthi Gangadhar,
• Sayini Ramakrishna,
• Ponneri Venkateswarlu and
• Pabbaraja Srihari

Beilstein J. Org. Chem. 2018, 14, 2313–2320, doi:10.3762/bjoc.14.206

• the first enantioselective total synthesis of the two diacetylenic diol natural products strongylodiol H and strongylodiol I and of an enantiomer of strongylodiol H. Our synthesis assisted us to revise the structure of both natural products strongylodiol H and I. The synthetic procedure involved the

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

• enantioselectivity [1][2]. Probably the most effective approach in stereoselective synthesis is enantioselective catalysis, because cheap prochiral starting materials can be converted into chiral enantiopure products and no undesirable side products are formed [3][4]. Therefore, the development of new ligands is

• efficient catalysts in various asymmetric reactions, for instance allylic substitution and enantioselective hydrogenation [9]. They were also applied in the stereoselective synthesis of complex natural products [10][11][12]. PHOX ligands are nonsymmetrical ligands which can coordinate to a metal center

• starting from D-fructose. Two of these ligands were applied in enantioselective catalysis. Results and Discussion Starting from D-fructose, 1,2-isopropylidene-protected pyranosides with different protective groups (PG) at C-3, C-4 and C-5 can be prepared in two to four steps (Scheme 1). First, D-fructose

Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry

• Michael K. Bogdos,
• Emmanuel Pinard and
• John A. Murphy

Beilstein J. Org. Chem. 2018, 14, 2035–2064, doi:10.3762/bjoc.14.179

• exact definition of a reaction employed in LSF, Jiang and co-workers have described a procedure that allows the enantioselective aerobic olefination of α-amino sp3 C–H bonds, using cooperative asymmetric and organocatalysed photoredox catalysis (Scheme 29) [73]. This may not allow for direct

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

• -epoxides [16]. Trost et al. disclosed the synthesis of dinuclear zinc complexes 3 and their application to enantioselective Aldol reactions [17][18] and a host of other asymmetric transformations [18]. Other notable contributions in this area were provided by the groups of Martell [19][20], Maruoka [21][22

• 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