New Procedure for Synthesis of 1,4-Dienes and Monoolefins via Methylcopper-Induced Cross-Coupling of Alkenylboranes with Organic Halides

Article abstract of DOI:10.1021/jo01297a021

The treatment of dialkenylchloroboranes (1) with 3 equiv of methylcopper at -30 to <*>-40 deg C followed by addition of allylic halides gave 1,4-dienes.In the case of simple alkyl halides, the cross-coupling products were obtained with the aid of PhSLi or P(OEt)3.A similar cross-coupling reaction of alkenyl-9-BBN (13) with allylic halides was realized by the use of 1 equiv of methylcopper, while cross-coupling with alkyl halides failed even in the presence of ligands.Systems such as dialkenylchloroborane-methylcopper and alkenyl-9-BBN-methylcopper reacted withsubstituted allylic halides predominantly at a γ position.The regioselectivity of the former system was quite similar to that of the free alkenylcopper, while the regioselectivity of the latter system was greater than that of the free alkenylcopper.These results clearly indicate that the reactive intermediate of the latter system is an ate complex such as 19.