Aminohaloboranes, easily prepared from anilines, imines, ketones or alkylnitriles, and boron trichloride or diethylaminodichloroborane, were found to be a convenient species for C-C bond formation reaction in both aromatic and aliphatic series. Namely,
N-anilinophenylchloroboranes and
N- alkylaminodichloroboranes reacted smoothly in the presence of triethylamine with benzaldehydes and isonitriles, probably via a cyclic transition state giving 2-aminobenzhydrols and 2-
N-alkylaminobenzaldehydes, respectively. A simple directed aldol reaction using vinylaminodichloroboranes and diethylaminovinyloxychloroboranes and a unique aldol-type reaction of alkylnitriles using diethylaminodichloroborane were performed under mild conditions. Using chiral vinylaminodichloroboranes made possible a very simple enantioselective aldol condensation reaction.
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