The newly developed chiral ligands 1 and 4 show opposite enantioselectivity in the asymmetricreduction of prochiral ketones resulting in the production of either enantiomer depending on the metal complex with high enantiomeric excess.
Highly Enantioselective Titanium-Catalyzed Cyanation of Imines at Room Temperature
作者:Abdul Majeed Seayad、Balamurugan Ramalingam、Kazuhiko Yoshinaga、Takushi Nagata、Christina L. L. Chai
DOI:10.1021/ol902540h
日期:2010.1.15
A highly active and enantioselective titanium-catalyzed cyanation of imines at roomtemperature is described. The catalyst used is a partially hydrolyzed titanium alkoxide (PHTA) precatalyst together with a readily available N-salicyl-β-aminoalcohol ligand. Up to 98% ee was obtained with quantitative yields in 15 min of reaction time using 5 mol % of the catalyst. Various N-protecting groups such as
Synthesis of new tridentate chiral aminoalcohols by a multicomponent reaction and their evaluation as ligands for catalytic asymmetric Strecker reaction
Mannich-type reaction between phenols, paraformaldehyde, and β-aminoalcohols in the presence of LiCl afforded N-2-hydroxybenzyloxazolidines with high ortho-selectivity. Hydrolytic or reductive ring opening of the oxazolidines provided a series of N-salicyl-β-aminoalcohols in 84–92% overall yield. The synthesized compounds were evaluated as ligands for a titanium-catalyzed catalytic asymmetricStrecker reaction
TITANIUM COMPOUNDS AND PROCESS FOR CYANATION OF IMINES
申请人:Seayad Abdul Majeed
公开号:US20110319629A1
公开(公告)日:2011-12-29
The present invention relates to titanium catalysts for synthesis reactions produced by bringing a reaction mixture comprising a titanium alkoxide and a ligand in contact with water, wherein the ligand is represented by the general formula (e): wherein R
1
, R
2
, R
3
, and R
4
are independently a hydrogen atom, an alkyl group, or the like, and (A) represents a group with two or more carbon atoms. The titanium catalysts may be isolated in solid form and may be stored. The invention further relates to a process for cyanation of imines, wherein the process comprises reacting an imine with a cyanating agent in the presence of the titanium catalyst.
[EN] TITANIUM COMPOUNDS AND PROCESS FOR CYANATION OF IMINES<br/>[FR] COMPOSÉS DE TITANE ET PROCÉDÉ DE CYANATION DES IMINES
申请人:AGENCY SCIENCE TECH & RES
公开号:WO2010093327A1
公开(公告)日:2010-08-19
The present invention relates to titanium catalysts for synthesis reactions produced by bringing a reaction mixture comprising a titanium alkoxide and a ligand in contact with water, wherein the ligand is represented by the general formula (e), wherein R1, R2, R3, and R4 are independently a hydrogen atom, an alkyl group, or the like, and (A) represents a group with two or more carbon atoms. The titanium catalysts may be isolated in solid form and may be stored. The invention further relates to a process for cyanation of imines, wherein the process comprises reacting an imine with a cyanating agent in the presence of the titanium catalyst.