Ene reaction proceeds between 1-alkyl-1,2-propadienyl sulfides and aldehydes in the presence of BF3·OEt2 to afford 1,3-dienes possessing an alkylthio group. On the other hand, the reactions of 1-silyl-1,2-propadienyl sulfides with aldehydes or their dimethylacetals give aldol-type addition products, α-methylene acylsilanes.
Enereaction proceeds between α-alkylallenyl sulfides and enophiles such as aldehydes and Schiffs bases in the presence of Lewisacid to afford various 1,3-dienes.