NMR studies of TMS-halide activated organocopper compounds

Article abstract of DOI:10.1016/0022-328X(89)87041-X

Conjugate addition to methyl cinnamate in the reactions with methylcopper and lithium dimethylcuprate activated by either trimethylchlorosilane (TMSCl) or trimethyliodosilane (TMSI) has been studied by 1H, 13C, and 29Si NMR spectroscopy.In the presence of TMSI, methylcopper adds to methyl cinnamate.In the reactions with TMSCl, the LiI usually present from the preparation of the methylcopper is necessary for the reaction to take place, and thus the iodine seems to play an important role in the process.The presence of LiI also influences the E/Z selectivity; reactions with MeCu/TMSI, in the absence of LiI give exclusively the Z isomer of the silyl ketene acetal.