Enhanced Rate and Selectivity by Carboxylate Salt as a Basic Cocatalyst in Chiral N-Heterocyclic Carbene-Catalyzed Asymmetric Acylation of Secondary Alcohols
摘要:
The rate and enantioselectivity of chiral NHC-catalyzed asymmetric acylation of alcohols with an adjacent H-bond donor functionality are remarkably enhanced in the presence of a carboxylate cocatalyst. The degree of the enhancement is correlated with the basicity of the carboxylate. With a cocatalyst and a newly developed electron-deficient chiral NHC, kinetic resolution and desymmetrization of cyclic diols and amino alcohols were achieved with extremely high selectivity (up to s = 218 and 99% ee, respectively) at a low catalyst loading (0.5 mol %). This asymmetric acylation is characterized by a unique preference for alcohols over amines, which are not converted into amides under the reaction conditions.
作者:Shuichi Takayama、Shelly T. Lee、Shang-Cheng Hung、Chi-Huey Wong
DOI:10.1039/a808028c
日期:——
A new strategy, utilizing IR and mass spectrometry, has been developed to design appropriate reagents and reaction conditions for enantioselective enzymatic protection of amines with readily removable protecting groups.
SYNTHETIC PROCESS FOR AMINOCYCLOHEXYL ETHER COMPOUNDS
申请人:Plouvier Bertrand M. C.
公开号:US20100152464A1
公开(公告)日:2010-06-17
Methods for the preparation of stereoisomerically substantially aminocyclohexyl ether compounds such as trans-(1R,2R)-aminocyclohexyl ether compounds and/or trans-(1S,2S)-aminocyclohexyl ether compounds as well as various intermediates and substrates are disclosed.