Synthesis of Optically Pure 3,3′-Disubstituted-1,1′-Bi-6-Methoxy-2-Phenol (BIPhOL) Derivatives via Diastereomeric Resolution

A new protocol for the enantioselective synthesis of 3,3'-disubstituted-1,1'-bi-6-methoxy-2-phenol (BIPhOL) derivatives is described. Diastereomeric resolution of racemic BIPhOL boronic acid using a boronic acid moiety as a resolving group generated two diastereomers and subsequent Suzuki-Miyaura coupling reaction of the resulting diastereomers with aryl halides provided BIPhOL derivatives without any loss of enantioselectivity. In addition, the absolute stereochemistry of chiral BIPhOL was determined by comparison of the optical rotation with the reported value.