Stereoselective hydrocoupling of [(1R)-exo]-3-exo-(diphenylmethyl)bornyl cinnamates by electroreduction.

[reaction: see text]. The chiral auxiliary [(1R)-exo]-3-exo-(diphenylmethyl)borneol, synthesized from (1R)-(+)-camphor in three steps, was highly effective for the stereoselective hydrocoupling of its cinnamates by electroreduction. From the resulting hydrodimers, (3R,4R)-3,4-diaryladipic acid esters and (3R,4R)-3,4-diarylhexane-1,6-diols were synthesized in 87-95% ee.