Chiral catalyst, process for preparing the same and its use in the oxidate coupling of naphthols
申请人:Gong Liuzhu
公开号:US20050256345A1
公开(公告)日:2005-11-17
The compound of this invention is a useful catalyst for the oxidative coupling of naphthol. Its originality lies in that it is a novel vanadium complex of Schiff's base formed by a chiral amino acid and a formyl biphenol or its derivative. Its axis chirality is induced to form by the chiral amino acid. It has the general formula:
where R represents a benzyl, an isopropyl, an isobutyl or a tertiary butyl and the configuration of the amino acid is R or S. The compound can catalyze oxidative coupling of naphthol or its derivative to form binaphthol or its derivatives with a high optical purity.
A family of optically pure 7,7'-disubsituted-2,2'-dihydroxy-1,1'-dinaphthyls have been conveniently prepared from easily accessible 7-alloxyl-2-naphthol by reaction sequences beginning with the asymmetric oxidative coupling and followed by key synthetic steps including deprotection, alkylation, and Suzuki coupling. Application of these binaphthols in catalytic phenylacetylene addition to aldehydes resulted in excellent enantioselectivities.
Novel Achiral Biphenol-Derived Diastereomeric Oxovanadium(IV) Complexes for Highly Enantioselective Oxidative Coupling of 2-Naphthols