An efficient access to ( R)- and ( S)-6,6′-dimethoxy-2,2′-diiodo-1,1′-biphenyl

Abstract

In a better procedure than the known for (rac)- 2a, the diamine (rac)- 2b was resolved for the first time with the new resolving agent ( R, R)- and ( S, S)-2,3-di(phenylamino-carbonyl)tartaric acid ( 5c) (40–45% weight yields; >99% ee). The diamines ( R)- or (S)- 2a and 2b were converted with >98% stereochemical retention into the diiodides ( R)- and (S)- 3a and 3b and subsequently, without loss of optical purity, diphenylphosphinated to the known diphosphines ( R)- and (S)- 4a and 4b.