295328-89-1Relevant academic research and scientific papers
Methods for the synthesis of chiral sulfur heterocycles and their application in the asymmetric Baylis-Hillman reactions
Periasamy, Mariappan,Gurubrahamam, Ramani,Muthukumaragopal, Gopal P.
, p. 568 - 574 (2013/06/27)
Enantiomerically pure (2S,6S)-2,6-diphenyltetrahydro-2H-thiopyran, (2S)-2-phenyltetrahydro thiophene, and (2S)-2-phenyltetrahydro-2H-thiopyran were prepared in 70-72% yields and with 86-99% ee via cyclization of the corresponding dimesylate in an SN2 cyclization reaction using sodium sulfide nonahydrate. The results on the application of various chiral sulfides in asymmetric Baylis-Hillman reactions are also described.
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.
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.
Asymmetric synthesis of planar chiral (arene)tricarbonylchromium complexes via enantioselective deprotonation by conformationally constrained chiral Lithium-amide bases
Pache, Sandrine,Botuha, Candice,Franz, Roberto,Kuendig, E. Peter,Einhorn, Jacques
, p. 2436 - 2451 (2007/10/03)
Enantioselective lithiation/electrophile addition reactions with eight chiral Li-amide bases, 1-8, and five [Cr(arene)(CO)3] complexes, 9-13, were investigated. Restriction of conformational freedom in the chiral Li-amide base Li-1, in general, did not result in an increase in asymmetric induction. A new route to enantiomerically enriched (75-92%) planar chiral ortho-substituted benzaldehyde complexes via enantioselective lithiation of benzaldimine complexes 16 and 17 is reported. Within the (1S)-enantiomer series of o-substituted benzaldehyde complexes 18a-d, the sign of the specific rotation, [α](D)/20, is found to be positive, except for the trimethylstannyl derivative 18b. This is interpreted in terms of a reversed conformation of the aldehyde group.
A simple enantioselective preparation of (2S,5S)-2,5-diphenylpyrrolidine and related diaryl amines
Aldous, David J.,Dutton, William M.,Steel, Patrick G.
, p. 2455 - 2462 (2007/10/03)
A short efficient catalytic asymmetric route to the preparation of C2-symmetric diaryl cyclic amines is described. Copyright (C) 2000 Elsevier Science Ltd.
