The reaction of chlorodimethylvinylsilane with tertbutyllithium was investigated in the presence of several conjugated dienes. In all cases except with 2,5-dimethylfuran, [2+4] cycloadducts of a silene intermediate are obtained in hydrocarbon solvents. The presence of THF in the reaction mixture suppresses the formation of cycloadducts in favor of 1,3-disilacyclobutanes. In the reaction of dimethylethoxyvinylsilane or dimethylmethoxyvinylsilane with tert-butyllithium the main product is the 1,1-dimethyl2-neopentyl-4-(dimethylalkoxysilyl)silacyclobutane. It is concluded that lithium chloride elimination to give silene intermediates occurs in hydrocarbon solvents. In the presence of strong Lewis bases or when the leaving group on silicon is an alkoxy group, the addition reaction giving a-lithiosilanes occurs and products arising from their coupling reactions are obtained.