Chiral nonracemic C2-symmetry biphenyls by desymmetrization of 6, 6', 2, 2'-tetramethoxy-1, 1'-biphenyl

Regioselective bromination of the title biphenyl 1 at the 3 and 3' positions and simultaneous desymmetrization of the biphenyl has been achieved. Metal-halide exchange at the 3,3' positions facilitated the introduction of functional groups in good yield. Regioselective reduction was obtained by using (CH3)(3)SiI, L-Selectride and HI according to the functional groups on the biphenyls. Resolution of 6,6',2,2'-tetramethoxy-3,3'-dimethyl-1,1'-biphenyl 3 was achieved by its conversion to the corresponding phosphorothioamidate diastereomers of the (S)-(-)-alpha -methylbenzylamine. The absolute configuration of (M)-(+)-3 was confirmed by X-ray analysis of the corresponding diastereomer.