Reactions of dilithiobutadienes with monochlorosilanes: Observation of facile loss of organic groups from silicon

Reactions of 1,4-dilithiobutadienes (from 1,4-diiodo-1,2,3,4-tetraethylbutadiene (1) and 2,2′-dibromobiphenyl (7) with t-BuLi) with Me₃SiCl gave siloles (3 and 9a) as the major products. No evidence for a disilylated butadiene was obtained. Use of higher molecular weight chlorosilanes ((allyl)Me₂SiCl, BnMe₂SiCl, and PhMe₂SiCl) with dibromide 7 gave dimethylsilole 9a and a silane (10a, 10b, or 10c) resulting from trapping of the organic group by the chlorosilane.