Investigation of oxacycle formation by base-promoted endo-mode ring-closing reaction of allenes

The base-promoted endo-mode ring closure of electron-withdrawing group-substituted allenes provided the following interesting results: (1) the endo-mode ring-closing reaction of 1-(benzyloxycarbonyl)-1-(ω-hydroxyalkyl)allenes smoothly proceeded during the formation of five-, seven-, and eight-membered rings; (2) base treatment of benzyloxycarbonylallene and sulfonylallene, having a 2-hydroxyethyl group at the C-1 position, in the presence of an aldehyde led to the ring closure and condensation with the aldehyde in one-pot; and (3) endo-mode ring closure of the sulfonylallenes by internal attack of the carboxylate anion afforded the six-membered lactone.