Synthesis of 1,7-dioxaspiro[5.5]undecanes and 1-oxa-7-thiaspiro[5.5]undecanes from exo-glycal

A new spirocyclization was developed for the synthesis of 1,7-dioxaspiro[5.5]undecanes and 1-oxa-7-thiaspiro[5.5]undecanes by reaction of exo-glycal with aryl alcohols or thiophenols in the presence of Lewis acid BF(3)-OEt(2). The reaction proceeded through tandem Ferrier rearrangement, glycosylation, and Friedel Crafts alkylation to provide the corresponding products in good to excellent yields. Crown Copyright (C) 2010 Published by Elsevier Ltd. All rights reserved.