Preparation of 3-oxo-2-cyclohexen-2-ylzinc iodides and their palladium-mediated reactions with aryl or alkenyl halides

2-Iodo-2-cyclohexen-1-ones 10 react under mild conditions with a large excess (4 equiv.) of an activated Zn(Ag) couple in the presence of TMEDA (1 equiv.) leading to the corresponding 3-oxo-2-cyclohexen-2-ylzinc iodides 11 in good yields. These new organozinc reagents can also be prepared in high yields by reaction of 10 and TMEDA (1 equiv.) with a large excess (4 equiv.) of 98% pure zinc dust (< 10 micron), which must be activated with chlorotrimethylsilane. In the presence of a palladium(0) catalyst precursor, compounds 11 undergo cross-coupling reactions with aryl or alkenyl halides bearing a variety of functional groups to give in moderate to high yields the desired 2-substituted 2-cyclohexen-1-ones 12. (C) 1997 Elsevier Science S.A.