Enantioselective conjugate hydrocyanation of α,β-unsaturated N-acylpyrroles with the combined use of Me3SiCN, LiCN, and HCN has been developed in the presence of a chiral lithium(I) phosphoryl phenoxide catalyst. This reaction is useful for a variety of N-acylpyrroles, including previously unreported substrates, such as heteroaryl and halogen-substituted N-cinnamoylpyrroles. A gram-scale reaction and
Toward a rational design of the assembly structure of polymetallic asymmetric catalysts: design, synthesis, and evaluation of new chiral ligands for catalytic asymmetric cyanation reactions
New chiral ligands (4 and 5) for polymetallic asymmetric catalysts were designed based on the hypothesis that the assembled structure should be stable when made from a stable module 8. A metal-ligand 5:6+mu-oxo+OH complex was generated from Gd((OPr)-Pr-i)(3) and 4 or 5, and this complex was an improved asymmetric catalyst for the desymmetrization of meso-aziridines with TMSCN and conjugate addition of TMSCN to alpha,beta-unsaturated N-acylpyrroles, compared to the previously reported catalysts derived from 1-3. These two groups of catalysts produced opposing enantioselectivity even though the ligands had the same chirality. The functional difference in the asymmetric catalysts is derived from differences in the higher-order structure of the polymetallic catalysts. (C) 2007 Elsevier Ltd. All rights reserved.
EP1995250
申请人:——
公开号:——
公开(公告)日:——
Ligand, Method for Producing the Same, and Catalyst Using the Ligand
申请人:Shibasaki Masakatsu
公开号:US20090023579A1
公开(公告)日:2009-01-22
Disclosed is a novel asymmetric ligand which can be synthesized by a short process at low cost and is capable of exhibiting higher catalytic activity and enantioselectivity than the conventional ligands derived from sugars. Also disclosed are a method for producing such an asymmetric ligand, and a catalyst using such an asymmetric ligand. Specifically disclosed is a ligand represented by the general formula I below or the like. (In the formula, R
1
and R
2
independently represent 0-5 substituents; X represents P, As or N; m represents an integer of 0-7; n represents an integer of 0-3; A
1
-A
4
independently represent hydrogen, fluorine, chlorine, bromine, benzoyl or acetyl, or alternatively A
2
and A
3
combine together to form a ring.)