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

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(phenylaminocarbonyl)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 purify, diphenylphosphinated to the known diphosphines (R)- and (S)-4a and 4b. Copyright (C) 1996 Elsevier Science Ltd