Chiral Magnesium BINOL Phosphate-Catalyzed Phosphination of Imines: Access to Enantioenriched α-Amino Phosphine Oxides
摘要:
A new method to synthesize chiral alpha-amino phosphine oxides is reported. The reaction combines N-substituted imines and diphenylphosphine oxide and is catalyzed by a chiral magnesium phosphate salt. A wide variety of aliphatic and aromatic aldimines substituted by electron-neutral benzhydryl or dibenzocycloheptene groups were excellent substrates for the addition reaction. The dibenzocycloheptene protected imines afforded improved enantioselectivity in the resulting products. Substituted diphenylphosphine oxide nucleophiles also showed good reactivity.
Mapping the Active Site in a Chemzyme: Diversity in the <i>N</i>-Substituent in the Catalytic Asymmetric Aziridination of Imines
作者:Yu Zhang、Zhenjie Lu、Aman Desai、William D. Wulff
DOI:10.1021/ol802431v
日期:2008.12.4
The active site of the aziridination catalyst derived from either the VANOL or VAPOL ligand and B(OPh)(3) is larger than expected and can accommodate not only significant substitution on the diarylmethyl unit of the imine but also that alkyl (but not perfluorylalkyl) substituents on the aryl groups lead to enhanced rates and enantioselection. The screen of diarylmethyl N-substituents on the imine revealed that the 3,5-di-tert-butyldianisylmethyl group (BUDAM) gave exceptionally high asymmetric inductions for imines of aryl aldehydes.