Relevant bibliographies by topics / Stereogenic quaternary center

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  1. Journal articles
  2. Dissertations / Theses
  3. Book chapters
  4. Conference papers

Academic literature on the topic 'Stereogenic quaternary center'

Author: Grafiati
Published: 4 June 2021
Last updated: 1 February 2022

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Journal articles on the topic "Stereogenic quaternary center"

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Chen, Hui, Cui Wang, Dongwa Wen, Yabo Deng, Xin Liu, Xueting Liu, Jiang Zhang, and Wenjin Yan. "The Catalytic Asymmetric Construction of Trifluoromethylated Quaternary Carbon-Containing Thiochromans." Synthesis 51, no. 17 (May 15, 2019): 3327–35. http://dx.doi.org/10.1055/s-0037-1611547.

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Trifluoromethylated chiral quaternary stereogenic carbon center at 2-position of thiochromans has been constructed through organocatalyzed Michael-aldol reaction. With quinine squaramide as catalyst, the reaction of 2-mercaptobenzaldehyde with β-aryl-β-CF3 enones or β-alkyl-β-CF3 enones gave 2-CF3-thiochromans bearing three contiguous stereogenic centers in good to excellent diastereoselectivities, enantioselectivities, and yields.
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Rafiński, Zbigniew. "NHC-Catalyzed Organocatalytic Asymmetric Approach to 2,2-Disubstituted Benzofuran-3(2H)-ones Containing Fully Substituted Quaternary Stereogenic Center." Catalysts 9, no. 2 (February 20, 2019): 192. http://dx.doi.org/10.3390/catal9020192.

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A highly efficient and enantioselective approach to the synthesis of functionalized benzofuran-3(2H)-ones is presented. It proceeds via an intramolecular Stetter reaction using β,β-disubstituted Michael acceptors in the construction of five-membered rings with fully-substituted quaternary stereogenic centers and is promoted by terpene-derived triazolium salts. As a result, a series of chiral 2,2-disubstituted benzofuran-3(2H)-one derivatives with linear, branched, and cyclic aliphatic substitutions on the quaternary stereogenic center were obtained in high yields and with excellent enantioselectivities of up to 99% ee.
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Yang, Mengchen, Chen Chen, Xing Yi, Yuan Li, Xiaoqin Wu, Qingshan Li, and Shurong Ban. "Thiosquaramide-catalysed asymmetric double Michael addition of 2-(3H)-furanones to nitroolefines." Organic & Biomolecular Chemistry 17, no. 11 (2019): 2883–86. http://dx.doi.org/10.1039/c9ob00330d.

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Jakhar, Ajay, Prathibha Kumari, Mohd Nazish, Noor-ul H. Khan, Rukhsana I. Kureshy, Sayed H. R. Abdi, and E. Suresh. "Catalytic asymmetric synthesis of enantioenriched β-nitronitrile bearing a C-CF3 stereogenic center." RSC Advances 6, no. 36 (2016): 29977–82. http://dx.doi.org/10.1039/c6ra00093b.

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Liu, Ming-Qing, Tao Jiang, Wen-Wen Chen, and Ming-Hua Xu. "Highly enantioselective Rh/chiral sulfur-olefin-catalyzed arylation of alkyl-substituted non-benzofused cyclic N-sulfonyl ketimines." Organic Chemistry Frontiers 4, no. 11 (2017): 2159–62. http://dx.doi.org/10.1039/c7qo00555e.

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Shimizu, Masahiro, Jun Kikuchi, Azusa Kondoh, and Masahiro Terada. "Chiral Brønsted acid-catalyzed intramolecular SN2′ reaction for enantioselective construction of a quaternary stereogenic center." Chemical Science 9, no. 26 (2018): 5747–57. http://dx.doi.org/10.1039/c8sc01942h.

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Construction of a quaternary stereogenic center was accomplished through the enantioselective intramolecular allylic substitution reaction of bis-trichloroacetimidate catalyzed by a chiral phosphoramide derivative.
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Štacko, Peter, Jos C. M. Kistemaker, and Ben L. Feringa. "Fluorine-Substituted Molecular Motors with a Quaternary Stereogenic Center." Chemistry - A European Journal 23, no. 27 (May 2, 2017): 6643–53. http://dx.doi.org/10.1002/chem.201700581.

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Liu, Yao, and Honggen Wang. "Unified enantioselective total syntheses of (−)-scholarisine G, (+)-melodinine E, (−)-leuconoxine and (−)-mersicarpine." Chemical Communications 55, no. 24 (2019): 3544–47. http://dx.doi.org/10.1039/c8cc09949a.

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A unified strategy enabled the enantioselective syntheses of (−)-scholarisine G, (+)-melodinine E, (−)-leuconoxine and (−)-mersicarpine from a common 2-alkylated indole bearing an all-carbon quaternary stereogenic center.
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Gui, Hou-Ze, Yin Wei, and Min Shi. "Construction of spirothioureas having an amino quaternary stereogenic center via a [3 + 2] annulation of 3-isothiocyanato oxindoles with 2-aminoacrylates." Organic & Biomolecular Chemistry 16, no. 47 (2018): 9218–22. http://dx.doi.org/10.1039/c8ob02748j.

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A [3 + 2] annulation of 3-isothiocyanato oxindoles with 2-aminoacrylates was disclosed, affording the corresponding spirocyclic oxindoles containing a spirothiourea structure and an amino quaternary stereogenic center in good to excellent yields.
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Wu, Xiao-Yun, Hou-Ze Gui, Harish Jangra, Yin Wei, Hendrik Zipse, and Min Shi. "Phosphine-catalyzed [3 + 2] annulation of 2-aminoacrylates with allenoates and mechanistic studies." Catalysis Science & Technology 10, no. 12 (2020): 3959–64. http://dx.doi.org/10.1039/d0cy00092b.

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A phosphine catalyzed formal [3 + 2] annulation was disclosed, affording 3-pyrrolines containing an amino quaternary stereogenic center in good to excellent yields. The catalytic mechanism was investigated by DFT and kinetic studies.
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Dissertations / Theses on the topic "Stereogenic quaternary center"

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Dabrowski, Jennifer A. "Development of Selective Methods to Form C-C Bonds. Enantioselective Formation of Tertiary and Quaternary Stereogenic Centers." Thesis, Boston College, 2013. http://hdl.handle.net/2345/3771.

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Thesis advisor: Amir H. Hoveyda
Formation of C-C bonds is an invaluable tool for the construction of materials, pharmaceuticals, natural products, and the building blocks of life. Although great strides in this area have been made, there remain several limitations in regio-, site-, and enantioselective additions of carbon-based nucleophiles. Solving these challenges by expanding the scope, efficiency, and selectivity of alkyl, aryl, heteroaryl, vinyl, and alkynyl additions to carbon-based electrophiles is the topic of this dissertation
Thesis (PhD) — Boston College, 2013
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry
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May, Tricia Lee. "Copper-Based N-Heterocyclic Carbene Complexes for Catalytic Enantioselective Conjugate Additions of Alkyl-, Aryl- and Vinyl-Based Nucleophiles to Form All-Carbon Quaternary Stereogenic Centers." Thesis, Boston College, 2011. http://hdl.handle.net/2345/2650.

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Thesis advisor: Amir H. Hoveyda
Chapter 1 Enantioselective Conjugate Additions of Carbon Nucleophiles to Activated Olefins: Preparation of Enantioenriched Compounds Containing All-Carbon Quaternary Stereogenic Centers. Methods for enantioselective conjugate addition of nucleophiles to activated olefins generating products containing all-carbon quaternary stereogenic centers are critically reviewed. Enantioselective conjugate addition has been shown to be a powerful and concise approach to construct carbon-carbon bonds to prepare compounds containing sterically hindered stereogenic centers and has seen great advances in the past several years. Owing to the difficult nature of additions to relatively unreactive conjugate acceptors, compared to additions generating tertiary stereogenic centers, and construction of a sterically-hindered bond, in many cases, new and active catalysts had to be developed. The review discusses the areas where significant advances have been made as well as current limitations and future outlook. Chapter 2 Development of New and Active Catalysts for Cu-Catalyzed Enantioselective Conjugate Addition of Alkyl- and Arylzinc Reagent. Through development of new chiral catalysts, we have found an active and enantiodiscriminating bidentate, sulfonate-containing NHC-Cu catalyst that effects enantioselective conjugate addition of alkyl- and arylzinc reagents on notoriously difficult trisubstituted cyclic enones. Products are prepared with high levels of selectivity and participate in a variety of further functionalizations. The enantioselective additions are efficient and practical, not requiring rigorously anhydrous or oxygen-free conditions. Chapter 3 Cu-Catalyzed Enantioselective Conjugate Addition of Alkyl- and Arylaluminum Reagents to Trisubstituted Enones. Outlined in this chapter is the first effective solution for Cu-catalyzed enantioselective addition of alkyl and aryl nucleophiles to trisubstituted cyclopentenones generating products bearing a β-all-carbon quaternary stereogenic center. Products are obtained in up to 97% yield and 99:1 er, only requiring 5 mol % of an in situ generated Cu-NHC catalyst. The methodology was highlighted as one of the key steps in the total synthesis of clavirolide C. Not only five-membered rings, but six- and seven-membered rings serve as proficient partners in the enantioselective process. Moreover, in cases for the enantioselective aryl addition, in situ prepared Me2AlAr can be used without purification, filtration, or isolation, only requiring the corresponding aryl halides. The additions have also been extended to trisubstituted unsaturated lactones and chromones. Chapter 4 Cu-Catalyzed Enantioselective Conjugate Addition of Vinylaluminum Reagents to Cyclic Trisubstituted Enones. An enantioselective protocol for the formation of β,β-disubstituted cyclic ketones containing a synthetically versatile vinylsilane is disclosed. Enantioselective conjugate addition of in situ prepared silyl-substituted vinylaluminum reagents to β,β-unsaturated ketones promoted by 5 mol % of chiral Cu-NHC complexes delivers desired products with high efficiency (up to 95% yield after purification) and enantioselectivities (up to >98:<2 er). Several functionalizations utilizing the vinylsilanes, vicinal to an all-carbon quaternary stereogenic center, are shown, including an oxidative rearrangement, vinyl iodide formation and protodesilylation, accessing products not previously attainable. Furthermore, the enantioselective protocol is demonstrated as the key transformation in the total synthesis of riccardiphenol B
Thesis (PhD) — Boston College, 2011
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry
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Mandai, Kyoko. "Cu-Catalyzed Enantioselective Allylic Substitutions with Organomagnesium and Organoaluminum Reagents Promoted by N-Heterocyclic Carbenes for the Formation of Quaternary Stereogenic Centers." Thesis, Boston College, 2010. http://hdl.handle.net/2345/1329.

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Thesis advisor: Amir H. Hoveyda
Chapter One: An overview of Cu-catalyzed enantioselective allylic substitutions with organometallic reagents. Chapter Two: Development of Cu-catalyzed enantioselective allylic alkylations of allylic chlorides with Grignard reagents for the formation of all-carbon quaternary stereogenic centers is disclosed. Chapter Three: Development of Cu-catalyzed enantioselective allylic substitutions of allylic phosphates with alkyl, aryl, and heterocyclic aluminum reagents for the formation of quaternary stereogenic centers is discussed
Thesis (MS) — Boston College, 2010
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry
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Song, Tao. "Alkylation allylique asymétrique pallado-catalysée : contrôle de centres quaternaires au sein d'hétérocycles azotés." Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLET012.

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Le développement d’outils synthétiques permettant le contrôle de centres stéréogènes quaternaires reste un défi important en synthèse organique. Dans ce contexte, l’alkylation allylique asymétrique pallado-catalysée est apparue comme une méthode particulièrement efficace. Le premier chapitre de cette thèse est consacré à l’application de cette réaction d’alkylation allylique asymétrique à des dérivés de type succinimides. Cette méthode, convergente, nous a permis d’accéder à un grand nombre de composés de type succinimide comportant un centre stéréogène quaternaire en position alpha avec de bons rendements et d’excellents excès énantiomériques. Par ailleurs, afin de démontrer l’intérêt synthétique de la méthode, ces composés allylés ont pu être transformés en diverses briques moléculaires d’intérêt parmi lesquelles des pyrrolidines et des dérivés spirocycliques optiquement actifs. Le second chapitre à quant à lui été consacré à l’application de cette même réaction d’alkylation allylique asymétrique à des dérivés de type 2-siloxypyrroles alpha,gamma-disubstitués dans le but de pouvoir accéder à des gamma-lactames enantioenrichies comportant un centre quaternaire en position alpha de manière efficace. Ces derniers ont par la suite pu être convertis en pyrrolidines et des pipéridines optiquement actives.Mots-clés: catalyse asymétrique, alkylation allylique, palladium, succinimides, lactames, centres stéréogènes quaternaires
The development of new synthetic tools allowing to create quaternary stereogenic centers remains an important challenge in synthetic organic chemistry. In this context, the palladium-catalyzed asymmetric allylic alkylation has become a particularly effective tool. The first chapter of this thesis is focused on the application of this key reaction to succinimide type compounds. This convergent method has allowed us to access a number of succinimide derivatives bearing a quaternary stereogenic center in high yields and excellent enantioselectivities. Moreover, in order to demonstrate the synthetic utility of the method, the resulting alpha-quaternary succinimides were converted to various useful building block including pyrrolidines and spirocyclic frameworks. The second chapter is focused on the application of the palladium-catalyzed asymmetric allylic alkylation to alpha,gamma-disubstituted 2-siloxypyrroles in order to access gamma-lactams bearing an alpha-quaternary stereogenic center in high yields and enantioselectivities. The latter were eventually converted to the corresponding pyrrolidines and pipéridinesKeywords: asymmetric catalysis, allylic alkylation, palladium, succinimides, lactams, all-carbon quaternary stereogenic centers
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Wieland, Laura Caroline. "Catalytic enantioselective synthesis of O- and N-substituted quaternary carbon stereogenic centers : 1. AL-catalyzed alkylations of α-ketoesters with dialkylzinc reagents. 2. AG-catalyzed vinylogous Mannich-type reactions of α-ketoimine esters with siloxyfurans." Thesis, Boston College, 2008. http://hdl.handle.net/2345/356.

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Thesis advisor: Amir H. Hoveyda
Chapter 1: We disclose an Al-catalyzed enantioselective method for additions of Me2Zn and Et2Zn to α-ketoesters bearing aromatic alkenyl, and alkyl substituents. These transformations are promoted in the presence of a readily available amino acid-based ligand, and afforded the desired products in excellent yields and in up to 95% ee. In addition, we discovered a remarkable enhancement of efficiency and selectivity in the presence of an achiral phosphoramidate additive. Chapter 2: An efficient diastereo- and enantioselective Ag-catalyzed method for additions of a commercially available siloxyfuran to α-ketoimine esters is disclosed. Catalytic transformations require an inexpensive metal salt (AgOAc) and an air stable chiral ligand that is readily prepared in three steps from commercially available materials in 42% overall yield. Aryl- as well as heterocyclic substituted ketoimines can be used effectively in the Ag-catalyzed process. Additionally, two examples regarding reactions of alkyl-substituted ketoimines are presented. An electronically modified N-aryl group is introduced that is responsible for high reaction efficiency (>98% conversion, 72–95% yields after purification), diastereo- (up to >98:2 dr) and enantioselectivity (up to 97:3 er or 94% ee). The new N-aryl unit is also crucial for conversion of the asymmetric vinylogous Mannich products to the unprotected amines in high yields. Spectroscopic and X-ray data are among the physical evidence provided that shed light on the identity of the Ag-based chiral catalysts and some of the mechanistic subtleties of this class of enantioselective C–C bond forming processes
Thesis (PhD) — Boston College, 2008
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry
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Wang, Gang. "Diastereoselective synthesis of Ribo-like nucleoside analogues bearing an all-carbon C3′ quaternary center." Thesis, 2020. http://hdl.handle.net/1866/25442.

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Les analogues de nucléosides ont reçu une attention particulière en raison de leurs importantes applications anticancéreuses et antivirales. Dans cette thèse, de nouveaux analogues nucléosidiques de type 1′,2′-cis et 1′,2′-trans ribo portant un centre stéréogénique quaternaire fonctionnalisé en position C3′ ont été synthétisés par des réactions de N-glycosylation stéréosélectives, qui ont été contrôlées en installant différents types de groupes protecteurs sur le C2′ substituant hydroxyle. Le précurseur acyclique critique de 2,4-syn diol a été obtenu par réduction diastéréosélective d’une β-hydroxycétone en utilisant la délivrance d'hydrure intermoléculaire. Une approche pour une séparation facile des 2,4-syn et 2,4-anti diols par protection/déprotection acétonide a été établie, de sorte que le 2,4-syn diol pur puisse être rapidement accessible par oxydation allylique successive et protection acétonide. Une stratégie alternative a également été développée pour la préparation d'analogues nucléosidiques en C1′-β de type ribo portant un centre quaternaire C3′ avec un groupe hydroxyle C5′ libre. Dans cette stratégie, les diacétates de type ribo ont servi de donneur de glycosyle qui ont été synthétisés à partir d’une époxydation diastéréosélective d’un précurseur de glycal. La réaction énantiosélective consécutive de Mukaiyama aldol et le transfert d'allyle intramoléculaire de radicaux libres catalysé par photoredox ont été établis et développés dans notre laboratoire pour installer le centre stéréogénique quaternaire. Des nucléosides 5′-triphosphates portant soit une purine soit une pyrimidine ont ensuite été synthétisés et sont testés contre le cancer et les infections virales. De plus, l'analogue L-1′,2′-cis-4′-thionucléoside portant un centre quaternaire stéréogénique fonctionnalisé en position C3′ avec un substituant hydroxyle en C2′ a été synthétisé par une stratégie acyclique avec 1′,2′-syn thioaminal précurseur, qui a subi une cyclisation intramoléculaire de type SN2 de type S1′→C4′. Le 1′,2′-syn thioaminal a été synthétisé par une addition de nucléobase diastéréosélective sur un dithioacétal.
Nucleoside analogues have received extensive attention due to their important anticancer and antiviral applications. In this thesis, novel 1′,2′-cis and trans ribo-like nucleoside analogues bearing an all-carbon C3′ quaternary stereogenic center were synthesized using stereoselective N-glycosylation reactions, which were controlled by installing different types of protecting groups on the C2′ hydroxyl substituent. The critical acyclic 2,4-syn diol precursor was obtained by diastereoselective reduction of a β-hydroxy ketone using intermolecular hydride delivery. An approach for easy separation of the 2,4-syn and 2,4-anti diols through acetonide protection/deprotection was established to rapidly access the pure 2,4-syn diol through successive allylic oxidation and acetonide protection. An alternative strategy was also developed for the preparation of ribo-like C1′-β nucleoside analogues bearing an all-carbon C3′ quaternary center with a free C5′ hydroxyl group. In this strategy, ribo-like diacetates served as the glycosyl donors which were synthesized from a diastereoselective epoxidation of a glycal precursor. A consecutive enantioselective Mukaiyama aldol reaction followed by a photoredox catalyzed free radical intramolecular allyl transfer were established and developed in our lab to install the all-carbon quaternary stereogenic center. Nucleoside 5′-triphosphates bearing either a purine or a pyrimidine nucleobase were then synthesized and are currently being tested against cancer and viral infections. In addition, L-1′,2′-cis-4′-thionucleoside analogues bearing an all-carbon C3′ stereogenic quaternary center along with a C2′ hydroxyl substituent were synthesized using an acyclic strategy from a 1′,2′-syn thioaminal precursor followed by a S1′→C4′ intramolecular SN2-like cyclization. The 1′,2′-syn thioaminal was synthesized by a diastereoselective nucleobase addition onto a dithioacetal.
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Lussier, Tommy. "Synthèse d’une nouvelle famille d’analogues de nucléosides pourtant un centre quaternaire en C3’." Thèse, 2019. http://hdl.handle.net/1866/22459.

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Cardinal-David, Benoit. "Création de centres stéréogéniques sur les molécules acycliques par contrôle du substrat : synthèse de centres quaternaires et d'analogues de nucléosides." Thèse, 2008. http://hdl.handle.net/1866/6565.

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Baiazitov, Ramil Yashnurovich. "Tandem double intramolecular [4+2]/[3+2] cycloaddition of nitro olefins : part I construction of piperidine rings, part II construction of vicinal quaternary stereogenic centers, part III progress toward a total synthesis of daphnilactone B /." 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3269837.

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Thesis (Ph. D.)--University of Illinois at Urbana-Champaign, 2007.
Source: Dissertation Abstracts International, Volume: 68-06, Section: B, page: 3788. Adviser: Scott E. Denmark. Includes bibliographical references (leaves 371-384). Available on microfilm from Pro Quest Information and Learning.
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Book chapters on the topic "Stereogenic quaternary center"

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Cramer, Nicolai, and Tobias Seiser. "Quaternary Stereogenic Centers by Enantioselective â-Carbon Eliminations fromtert-Cyclobutanols." In Asymmetric Synthesis II, 55–59. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2013. http://dx.doi.org/10.1002/9783527652235.ch8.

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Maciá, Beatriz. "Formation of Quaternary Stereocentres by Copper-Catalysed Enantioselective Conjugate Addition Reaction." In Progress in Enantioselective Cu(I)-catalyzed Formation of Stereogenic Centers, 41–98. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/3418_2015_158.

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Mortko, Christopher J., and Miguel A. Garcia-Garibay. "Engineering Stereospecific Reactions in Crystals: Synthesis of Compounds with Adjacent Stereogenic Quaternary Centers by Photodecarbonylation of Crystalline Ketones." In Topics in Stereochemistry, 205–53. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2006. http://dx.doi.org/10.1002/0471785156.ch7.

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Taber, Douglass. "Enantioselective Construction of Alkylated Stereogenic Centers." In Organic Synthesis. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199764549.003.0040.

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Carsten Bolm of RWTH Aachen developed (Angew. Chem. Int. Ed. 2008, 47, 8920) an Ir catalyst that effected hydrogenation of trisubstituted enones such as 1 with high ee. Benjamin List of the Max-Planck-Institut Mülheim devised (J. Am. Chem. Soc. 2008, 130, 13862) an organocatalyst for the enantioselective reduction of nitro acrylates such as 3 with the Hantzsch ester 4. Gregory C. Fu of MIT optimized (J. Am. Chem. Soc. 2008, 130, 12645) a Ni catalyst for the enantioselective arylation of propargylic halides such as 6. Both enantiomers of 6 were converted to the single enantiomer of 8. Michael C. Willis of the University of Oxford established (J. Am. Chem. Soc. 2008, 130, 17232) that hydroacylation with a Rh catalyst was selective for one enantiomer of the allene 9, delivering 11 in high ee. Similarly, José Luis García Ruano of the Universidad Autónoma de Madrid found (Angew. Chem. Int. Ed. 2008, 47, 6836) that one enantiomer of racemic 13 reacted selectively with the enantiomerically- pure anion 12, to give 14 in high diastereomeric excess. Ei-chi Negishi of Purdue University described (Organic Lett. 2008, 10, 4311) the Zr-catalyzed asymmetric carboalumination (ZACA reaction) of the alkene 15 to give the useful chiron 16. David W. C. MacMillan of Princeton University developed (Science 2008, 322, 77) an intriguing visible light-powered oxidation-reduction approach to enantioselective aldehyde alkylation. The catalytic chiral secondary amine adds to the aldehyde to form an enamine, that then couples with the radical produced by reduction of the haloester. Two other alkylations were based on readily-available chiral auxiliaries. Philippe Karoyan of the Université Pierre et Marie Curie observed (Tetrahedron Lett . 2008, 49, 4704) that the acylated Oppolzer camphor sultam 20 condensed with the Mannich reagent 21 to give 22 as a single diastereomer. Andrew G. Myers of Harvard University developed the pseudoephedrine chiral auxiliary of 23 to direct the construction of ternary alkylated centers. He has now established (J. Am. Chem. Soc. 2008, 130, 13231) that further alkylation gave 24, having a quaternary alkylated center, in high diastereomeric excess.
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Taber, Douglass F. "Arrays of Stereogenic Centers: The Barker Synthesis of (+)-Galbelgin." In Organic Synthesis. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780190200794.003.0043.

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Gang Zhao of the Shanghai Institute of Organic Chemistry and Gang Zou of the East China University of Science and Technology devised (Adv. Synth. Catal. 2011, 353, 3129) an elegant catalyst for the direct enantioselective epoxidation of a simple acyclic enone 1. Ismail Ibrahem and Armando Córdova of Mid Sweden University and Stockholm University prepared (Adv. Synth. Catal. 2011, 353, 3114) 6 by combining three catalysts to effect the enantioselective addition of 5 to 4. Giovanni Casiraghi and Franca Zanardi of the Università degli Studi di Parma used (J. Org. Chem. 2011, 76, 10291) a silver catalyst to mediate the addition of 8 to 7 to give 9. Keiji Maruoka of Kyoto University condensed (Nature Chem. 2011, 3, 642) the diazo ester 10 with an aldehyde 4, leading, after reduction of the initial adduct and protection, to the diamine 11. Christoph Schneider of the Universität Leipzig effected (Synthesis 2011, 4050) the vinylogous addition of 13 to an imine 12, setting both stereogenic centers of 14. In the course of the coupling of 16 with the diol 15, Michael J. Krische of the University of Texas established (J. Am. Chem. Soc. 2011, 133, 12795) four new stereogenic centers. By adding (Chem. Commun. 2011, 47, 10557) an α-nitro ester 18 to the maleimide 19, Professor Maruoka established both the alkylated secondary center and the N-substituted quaternary center of 20. Srinivas Hotha of the Indian Institute of Science Education & Research and Torsten Linker of the University of Potsdam showed (Chem. Commun. 2011, 47, 10434) that the readily prepared lactone 21 could be opened to 23 without disturbing the stereogenic center adjacent to the carbonyls. Allan D. Headley and Bukuo Ni of Texas A&M University-Commerce devised (Synthesis 2011, 1993) a recyclable catalyst for the addition of an aldehyde 7 to a nitroalkene 24 in water to give 25. Alexandre Alexakis of the University of Geneva effected (Chem. Commun. 2011, 47, 7212) the triply convergent coupling of 26, 27, and 28 to give 29 as a single dominant diastereomer.
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Taber, Douglass. "The Castle Synthesis of (-)-Acutumine." In Organic Synthesis. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199764549.003.0104.

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The complex tetracyclic alkaloid (-)-acutumine 3, isolated from the Asian vine Menispermum dauricum, shows selective T-cell toxicity. The two adjacent cyclic all-carbon quaternary centers of 3 offered a particular challenge. Steven L. Castle of Brigham Young University solved (J. Am. Chem. Soc. 2009, 131, 6674) this problem by effecting net enantioselective conjugate allylation of the enantiomerically pure substrate 1 to give 2 with high diastereocontrol. The starting coupling partners ( Organic Lett . 2006, 8, 3757; Organic Lett. 2007, 9, 4033) for the synthesis were the Weinreb amide 4, prepared over several steps from 2,3- dimethoxyphenol, and the diastereomerically- and enantiomerically-pure cyclopentenyl iodide 5, prepared by singlet oxygenation of cyclopentadiene followed by enzymatic hydrolysis. Transmetalation of 5 by the Knochel protocol, addition of the resulting organometallic to 4 and enantioselective (and therefore diastereoselective) reduction of the resulting ketone delivered the alcohol 6. Methods for installing cyclic halogenated stereogenic centers are not well developed. Exposure of the allylic alcohol to mesyl chloride gave the chloride 7 with inversion of absolute configuration. Remarkably, this chlorinated center was carried through the rest of the synthesis without being disturbed. A central step in the synthesis of 3 was the spirocyclization of 7 to 8. Initially, iodine atom abstraction generated the aryl radical. The diastereoselectivity of the radical addition to the cyclopentene was set by the adjacent silyloxy group. The α-keto radical so generated reacted with the Et3Al to give a species that was oxidized by the oxaziridine to the α-keto alcohol, again with remarkable diastereocontrol. Conjugate addition to the cyclohexenone 1 failed, so an alternative strategy was developed, diastereoselective 1,2-allylation of the ketone followed by oxy-Cope rearrangement. The stereogenic centers of 1 are remote from the cyclohexenone carbonyl, so could not be used to control the facial selectivity of the addition. Fortunately, the stoichiometric enantiomerically-pure Nakamura reagent delivered the allyl group preferentially to one face of the ketone 1, to give 9. The subsequent sigmatropic rearrangement to establish the very congested second quaternary center of 2 then proceeded with remarkable facility, at 0°C for one hour.
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7

Taber, Douglass F. "C–N Ring Construction: The Fujii/Ohno Synthesis of (–)-Quinocarcin." In Organic Synthesis. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780190200794.003.0056.

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Tsutomu Katsuki of Kyushu University devised (Org. Lett. 2012, 14, 4658) a Ru catalyst for the enantioselective aziridination of vinyl ketones such as 1. David W.C. MacMillan of Princeton University added (J. Am. Chem. Soc. 2012, 134, 11400) 3 to the alkene 4 under single electron conditions to give 5 with high stereocontrol. Barry M. Trost of Stanford University effected (J. Am. Chem. Soc. 2012, 134, 4941) the Pd-catalyzed addition of 7 to an imine 6 to give the pyrrolidine 8. More recently, he used (J. Am. Chem. Soc. 2013, 135, 2459) this approach to construct pyrrolidines containing defined quaternary centers. Christoph Schneider of the Universität Liepzig employed (Org. Lett. 2012, 14, 5972) an organocatalyst to control the relative and absolute configuration not only of the nitrogen-containing ring, but also of the stereogenic center on the sidechain of the pyrrolidone 11. Wei Wang of Lanzhou University also used (Adv. Synth. Catal. 2012, 354, 2635) an organocatalyst to assemble the pyrrolidine 14bearing two stereogenic centers. Using a gold catalyst, Constantin Czekelius of the Freie Universität Berlin constructed (Angew. Chem. Int. Ed. 2012, 51, 11149) the pyrrolidine 16 having a defined quaternary center. Motomu Kanai of the University of Tokyo used (J. Am. Chem. Soc. 2012, 134, 17019) a Cu catalyst to prepare both pyrrolidines and piperidines by condensing the precursor protected aminal 17 with a ketone 18. Wolfgang Kroutil of the University of Graz effected (Angew. Chem. Int. Ed. 2012, 51, 6713) selective enzymatic reductive amination of the methyl ketone of 20 to give, after cyclization and hydrogenation, the 2,6-dialkyl piperidine 21. Ramakrishna G. Bhat of the Indian Institute of Science Education and Research showed (J. Org. Chem. 2012, 77, 11349) that the reductive cyclization of the amino acid derivative could proceed with high diastereoselectivity to give 23. Peter O’Brien of the University of York and Iain Coldham of the University of Sheffield prepared (J. Am. Chem. Soc. 2012, 134, 5300) both pyrrolidines and piperidines by metalation of an aryl derivative such as 24, followed by alkylation. Shital K. Chattopadhyay of the University of Kalyani cyclized (J. Org. Chem. 2012, 77, 11056) the nitrone 26 to 27 with high diastereoselectivity.
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8

Taber, Douglass F. "Enantioselective Construction of Alkylated Centers: The Maier Synthesis of Platencin." In Organic Synthesis. Oxford University Press, 2013. http://dx.doi.org/10.1093/oso/9780199965724.003.0039.

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Jaesook Yun of Sungkyunkwan University devised (J. Org. Chem. 2009, 74, 4232) a method, based on conjugate addition to a cyano alkyne, for the preparation of nitriles such as 1 with high geometric control. Enantioselective conjugate reduction then delivered the doubly arylated stereogenic center of 2 in high ee. Pher G. Andersson of Uppsala University described (J. Am. Chem. Soc. 2009, 131, 8855) a similar approach to diarylated ternary stereogenic centers. Motomu Kanai and Masakatsu Shibasaki of the University of Tokyo developed (J. Am. Chem. Soc. 2009, 131, 3858) a complementary approach to dialkylated stereogenic centers based on enantioselective conjugate cyanation of α-methylene N-acylpyrroles such as 3. Cathleen M. Crudden of Queen’s University established (J. Am. Chem. Soc. 2009, 131, 5024) that a benzylic organoborane, prepared by enantioselective hydroboration of styrene, coupled with an aryl iodide such as 6 in good yield and with > 90% retention of ee. Kwunmin Chen of National Taiwan Normal University devised ( Adv. Synth. Cat. 2009, 351, 1273) an organocatalyst for the enantioselective Michael addition of an α,α,-dialkyl aldehyde such as 9 to a nitroalkene. Wenhu Duan of the East China University of Science and Technology and Wei Wang of the University of New Mexico together developed (Organic Lett. 2009, 11, 2864) an organocatalyst for the enantioselective addition of nitromethane 12 to an unsaturated ketone such as 11. Xiaodong Shi of West Virginia University found (Angew. Chem. Int. Ed. 2009, 48, 1279) that commercial diphenyl prolinol effectively promoted enantioselective conjugate addition of 15 to 14. Enantioselective methods for the construction of alkylated quaternary centers have also been put forward. Kin-ichi Tadano of Keio University devised (Tetrahedron Lett. 2009, 50, 1139) a glucose-derived chiral auxiliary that effectively directed the absolute sense of the alkylation of 17. Li Deng of Brandeis University reported (Tetrahedron 2009, 65, 3139) further details of his elegant Cinchona -mediated conjugate addition of 19 to 20. Francesca Marini of the Università degli Studi di Perugia extended (Adv. Synth. Cat. 2009, 351, 103) this approach to selenones, effecting, over two steps, enantioselective vinylation.
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9

Taber, Douglass. "Enantioselective Construction of Alkylated Centers." In Organic Synthesis. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199764549.003.0039.

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Unsaturated half acid esters such as 1 are readily prepared by Stobbe condensation between dialkyl succinate and an aldehyde. Johannes G. de Vries of DSM and Floris P. J. T. Rutjes of Radboud University Nijmegen observed (Adv. Synth. Catal. 2008, 350, 85) that these acids were excellent substrates for enantioselective hydrogenation. Kazuaki Kudo of the University of Tokyo designed (Organic Lett. 2008, 10, 2035) a resin bound peptide catalyst for the transfer reduction of unsaturated aldehydes such as 3 , using 4 as the net H2 donor. Note that 5 was produced with high enantiocontrol from 3 that was a ~ 2:1 mixture of geometric isomers. Motomu Kanai and Masakatsu Shibasaki of the University of Tokyo devised (J. Am. Chem. Soc. 2008, 130, 6072) a chiral Gd catalyst that mediated the conjugate cyanation of enones such as 6 with high ee. Eric N. Jacobsen of Harvard University prepared (Angew. Chem. Int. Ed. 2008, 47, 1762) a dimeric Al salen catalyst that showed improved activity over the monomeric catalysts. Even congested imides such as 8 could be cyanated efficiently, delivering alkylated quaternary stereogenic centers. Takahiro Nishimura and Tamio Hayashi of Kyoto University optimized (J. Am. Chem. Soc. 2008, 130, 1576) the Rh*-catalyzed enantioselective conjugate addition of silyl acetylenes to enones such as 10, to give 12. Adriaan J. Minnaard and Ben L. Feringa of the University of Groningen devised (Angew. Chem. Int. Ed. 2008, 47, 398) conditions for the enantioselective 1,6-conjugate addition of alkyl Grignard reagents to diene esters such as the inexpensive ethyl sorbate 14. The product 16 incorporated, in addition to the newly formed stereogenic center, a geometrically defined E alkene. William S. Bechara and André B. Charette of the Université de Montréal found (Organic Lett. 2008, 10, 2315) that alkyl Grignard reagents could be induced to add with high enantioselectivity to pyridyl sulfones such as 17. In a different approach, Gregory C. Fu of MIT developed (J. Am. Chem. Soc. 2008, 130, 3302; J. Am. Chem. Soc. 2008, 130, 2756) conditions for the enantioselective alkenylation of racemic bromo esters such as 19, The latter reference is to the analogous enantioselective coupling of organozinc bromides with racemic allylic chlorides.
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10

Taber, Douglass. "Synthesis of Dysiherbaine (Hatakeyama), Jerangolid D (Markó) and ( + )-Spirolaxine Me Ether (Trost)." In Organic Synthesis. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199764549.003.0049.

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Several new developments in enantioselective C-O ring construction have been applied in the syntheses of natural products. To achieve control, the oxygenated quaternary center of dysiherbaine 9 must be established under kinetic conditions. One approach would be SN2 opening, but this would require displacement at a fully-substituted center. Susumi Hatakeyama of Nagasaki University has shown (Chem. Commun. 2007, 4158) that the epoxide 6, prepared by the Sharpless procedure, undergoes just such an opening under mild acid catalysis. Another approach to highly-substituted tetrahydrofurans and tetrahydropyrans is to join two carbons of a preformed chiral ether, such as 18. This is the strategy that István E. Markó employed in his recent (J. Am. Chem. Soc. 2007, 129, 3516) synthesis of jerangolid D 22. The key step was the three-component coupling of 15, 16, and 17, using a protocol recently developed in his group. Again using a procedure his group had developed, the trisubstituted alkene of 21 was prepared by modified Julia coupling of the ketone 19 with the anion of sulfone 20, followed be esterification and reduction. The spiroketal ( + )-spiroxaline methyl ether 31 contains three secondary oxygenated stereogenic centers. In a showcase of current chiral technology, Barry M. Trost of Stanford University constructed (Angew. Chem. Int. Ed. 2007, 46, 7664) the first two of the three alcohols by the enantioselective addition of an alkyne to an aldehyde. The chiral catalyst 25 that directed the alkyne additions was derived from a commercial ligand. The last alcohol center was derived from R -( + )-epoxypropane. Note that the spiroketal was not prepared in the usual way, by acid-catalyzed cyclization of a dihydroxy ketone, but by Pd-catalyzed cyclization of the alkyne diol 30.
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Conference papers on the topic "Stereogenic quaternary center"

1

Palomo Nicolau, Claudio, Eider Badiola, Julen Etxabe, Aitor Landa, Antonia Mielgo, Iurre Olaizola, Iñaki Urruzuno, et al. "α’-Oxy Enones for Construction of All-Carbon Quaternary Stereogenic Centers: Azlactones as Pronucleophiles." In MOL2NET 2016, International Conference on Multidisciplinary Sciences, 2nd edition. Basel, Switzerland: MDPI, 2016. http://dx.doi.org/10.3390/mol2net-02-h001.

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