Chiral nonracemic C2-symmetry biphenyls by desymmetrization of 6,6′,2,2′-tetramethoxy-1,1′-biphenyl
作者:Giovanna Delogu、Davide Fabbri、Maria Antonietta Dettori、Alessandra Forni、Gianluigi Casalone
DOI:10.1016/s0957-4166(00)00410-9
日期:2000.11
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. (C) 2000 Elsevier Science Ltd. All rights reserved.