An unexpected allyl-transfer reaction under conditions of Lewis acid-promoted cyclization of homoallylic alcohols with aldehydes

The title reaction was observed along with cyclization in the SnCl₄-promoted reaction of 2-[3,4,6-tri-O-benzyl-2-deoxy-2-(p-tolylsulfanyl)-β-D-glucopyranosyl]ethanal with pent-4-en-2-ol and this result was interpreted in terms of anchimeric assistance by sulfur to the unusual fragmentation of an intermediate alkoxycarbenium ion.