A general approach to the (S)-and (R)-isoflavans was invented, and efficiency of the method was demonstrated by the synthesis of (S)-equol ((S)-3),(R)-sativan ((R)-4), and (R)-vestitol ((R)-5). The key step is the allylic substitution of (S)-6a (Ar1= 2, 4-(MeO) 2C6H3) and (R)-6b (Ar1= 2, 4-(BnO) 2C6H3) with copper reagents derived from CuBr· Me2S and Ar2-MgBr (7a, Ar2= 4-MeOC6H4; 7b, 2, 4-(MeO) 2C6H3; 7c, 2-MOMO-4-MeOC6H3), furnishing anti SN2 ...
