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 ...