295328-90-4Relevant academic research and scientific papers
Enantioselective Stetter Reactions Catalyzed by Bis(amino)cyclopropenylidenes: Important Role for Water as an Additive
Rezazadeh Khalkhali, Mehran,Wilde, Myron M. D.,Gravel, Michel
supporting information, p. 155 - 159 (2021/01/09)
The first highly enantioselective intermolecular Stetter reaction using simple enones is reported. A series of novel chiral BAC structures were designed and prepared. They were tested in the Stetter reaction with simple aldehydes and enones. The products were generated in excellent yields and enantioselectivities (up to 94% ee). Surprisingly, a substoichiometric amount of water was crucial to obtain high enantioselectivities. Chiral BACs were also shown to catalyze 1,6-conjugate addition reactions with paraquinone methides enantioselectively.
A general, enantioselective synthesis of 2-substituted thiomorpholines and thiomorpholine 1,1-dioxides
Reed, Carson W.,Lindsley, Craig W.
, (2019/09/10)
In the course of our drug discovery programs, we had need to access chiral, 2-substituted thiomorpholines and their oxidized congeners, thiomorpholine 1,1-dioxides. Here, we disclose a high-yielding, general protocol for the enantioselective synthesis of
Development of chiral bis-hydrazone ligands for the enantioselective cross-coupling reactions of aryldimethylsilanolates
Denmark, Scott E.,Chang, Wen-Tau T.,Houk,Liu, Peng
supporting information, p. 313 - 366 (2016/09/09)
A palladium-catalyzed, enantioselective, aryl-aryl cross-coupling reaction using 1-naphthyldimethylsilanolates and chiral bis-hydrazone ligands has been developed. A family of glyoxal bis-hydrazone ligands containing various 2,5-diarylpyrrolidine groups was prepared to evaluate the influence of ligand structure on the rate and enantioselectivity of the cross-coupling. New synthetic routes to the 1-amino-2,5-diarylpyrrolidines were developed to enable the structure/reactivity-selectivity studies. Role reversal experiments of aryldimethylsilanolates and aryl bromides result in biaryl products with the same configuration and similar enantioselectivities implying that reductive elimination is the stereodetermining step. The origin of stereoselectivity is rationalized through computational modeling of diarylpalldium(II) complex which occurs through a conrotatory motion for the two aryl groups undergoing C-C bond formation.
Mukaiyama-Michael reactions with acrolein and methacrolein: A catalytic enantioselective synthesis of the C17-C28 fragment of pectenotoxins
Kemppainen, Eeva K.,Sahoo, Gokarneswar,Valkonen, Arto,Pihko, Petri M.
supporting information; experimental part, p. 1086 - 1089 (2012/03/27)
Enantioselective iminium-catalyzed reactions with acrolein and methacrolein are rare. A catalytic enantioselective Mukaiyama-Michael reaction that readily accepts acrolein or methacrolein as substrates, affording the products in good yields and 91-97% ee, is presented. As an application of the methodology, an enantioselective route to the key C17-C28 segment of the pectenotoxin using the Mukaiyama-Michael reaction as the key step is described.
Phosphino hydrazones as suitable ligands in the asymmetric Suzuki-Miyaura cross-coupling
Ros, Abel,Estepa, Beatriz,Bermejo, Antonio,Alvarez, Eleuterio,Fernandez, Rosario,Lassaletta, Jose M.
scheme or table, p. 4740 - 4750 (2012/07/02)
Phosphino hydrazones derived from C2-symmetric hydrazines exhibit excellent catalytic activity and provide good enantioselectivities in the asymmetric Suzuki-Miyaura cross-coupling to axially chiral biaryls, in particular for the most challenging reactions of monocyclic, functionalized aryl bromides and triflates. X-ray analysis of preformed [Pd(P/N)Cl2] precatalysts [(P/N) = phosphino hydrazone] revealed a strong n-π conjugation in the hydrazone moiety, identified by a high planarity degree at the pyrrolidine N(sp3) atom, that makes rotations around N-N bonds inconsequential. The complexes are also characterized by an envelope-like conformation with the Pd atom placed at the opposite side to the 2-phenyl group on the nearest stereogenic center of the pyrrolidine group. The isolation and structural analysis of oxidative addition intermediates indicate that the configurational stability of Pd-C(Ar) bonds is dependent on the substitution pattern in the aryl bromide.
Design and synthesis of new bis-hydrazones and pyridine bis-hydrazones: Application in the asymmetric Diels-Alder reaction
Monge, David,Bermejo, Antonio,Vazquez, Juan,Fernandez, Rosario,Lassaletta, Jose M.
, p. 33 - 45 (2013/01/15)
The design of two different types of new chiral bis-hydrazones 5 (bidentate N,N ligands, type A) and pyridine bis-hydrazones 7 ('pincer' N,N,N ligands, type B) is discussed. Preliminary results on the copper(II)-catalyzed Diels-Alder reaction of N-(E)-crotyloxazolidin-2-one (8) with cyclopentadiene (9) revealed that the (2S,6S)-2,6-diphenylpiperidine C2-symmetric substructure in pyridine bis-hydrazone ligand 7c is the key design element leading to good enantioselectivities. ARKAT-USA, Inc.
Convenient methods for synthesis of C2-symmetric diphenyltetrahydrothiophenes
Periasamy, Mariappan,Ramani, Gurubrahamam,Muthukumaragopal, Gopal P.
scheme or table, p. 1739 - 1743 (2009/12/27)
Racemic and optically pure (-)-(3R,4R)-3,4-diphenyltetrahydrothiophene, (+)-(2S,5S)-2,5-diphenyltetrahydrothiophene, and (-)-(3S,6S)-3,6-diphenyl-1,2- dithiane were synthesized by use, in the crucial steps, of the easy-to-handle borane systems tetrabutylammonium borohydride-iodine and tetrabutylammonium borohydride-iodomethane. Georg Thieme Verlag Stuttgart.
A new class of chiral lewis basic metal-free catalysts for stereoselective allylations of aldehydes
Simonini, Valentina,Benaglia, Maurizio,Pignataro, Luca,Guizzetti, Stefania,Celentano, Giuseppe
scheme or table, p. 1061 - 1065 (2009/04/06)
A new class of amine N-oxides derived from trans-2,5-diphenylpyrrolidine were synthesized in enantiomerically pure form and tested as metal-free catalysts in the reaction of aldehydes with allyl(trichloro)silane to afford homoallylic alcohols. The products were obtained in fair to good yields and up to 85% ee. The behavior of structurally different catalysts and the influence of a coordinating unit present in the organocatalyst on controlling the stereochemical efficiency of the reaction were also investigated. Noteworthy a catalyst capable of promoting the allylation of aliphatic aldehydes with an almost unprecedent and unusually high enantioselectivity, up to 85%, was identified. Georg Thieme Verlag Stuttgart.
Olefination of ketenes for the enantioselective synthesis of allenes via an ylide route
Li, Chuan-Ying,Zhu, Ben-Hu,Ye, Long-Wu,Jing, Qing,Sun, Xiu-Li,Tang, Yong,Shen, Qi
, p. 8046 - 8053 (2008/02/08)
Pseudo-C2-symmetric chiral phosphorus ylide is designed and synthesized for the enantioselective preparation of allenic esters, amides, ketone, and nitrile. Up to 92% ee is achieved.
Enantioselective synthesis of allenic esters via an ylide route
Li, Chuan-Ying,Sun, Xiu-Li,Jing, Qing,Tang, Yong
, p. 2980 - 2982 (2008/09/20)
Pseudo-C2-symmetric chiral phosphorus ylides have been designed and synthesized for the enantioselective preparation of allenic esters, and up to 92% ee has been achieved. The Royal Society of Chemistry 2006.
