Motokazu Uemura

AXIALLY CHIRAL BENZAMIDES : DIASTEREOSELECTIVE NUCLEOPHILIC ADDITIONS TO PLANAR CHIRAL (N, N-DIETHYL-2-ACYL-6-METHYLBENZAMIDE)CHROMIUM COMPLEXES

Axially chiralN, N-diethyl-2-methyl-6-α-hydroxyalkylbenzamides were prepared as an enantiomerically pure form by nucleophilic additions to the planar chiral tricarbonylchromium-complexed 2-acyl (or formyl)-6-methylbenzamides. n nAxially chiral benzamides with secondary alcohol were stereoselectively prepared in enantiomerically pure form. nDownload full-size image

DIASTEREOSELECTIVE ORTHO-LITHIATION OF TRICARBONYLCHROMIUM COMPLEXES OF CHIRAL BENZALDEHYDE ACETALS

Abstract Both enantiomers of the planar chiral (2-bromo-3,5-dialkoxybenzaldehyde)chromium complexes were prepared by diastereoselective ortho -lithiation of tricarbonylchromium complexes of the chiral benzaldehyde acetals with high optical purity.

Asymmetric Synthesis of Axially Chiral Biaryls Utilizing Planar Chiral Arene Chromium Complexes

Axially chiral biaryls are stereoselectively prepared by utilizing planar chiral arene chromium complexes. Both enantiomers of an axial biaryl could be synthesized starting from a single enantiopure arene chromium complex, and this method is applied to the synthesis of the vancomycin A-B ring system and korupensamines.

Inversion of Planar Chirality vs Axial Isomerization of Axially Chiral Biaryl Chromium Complexes

syn-Biaryl chromium complexes having a coordinating ortho-substituent gave anti-biaryl chromium complexes 5 with an inversion of the planar chirality by heating in a non-aromatic solvent.