Amberlyst-15-catalyzed intramolecular SN2′ oxaspirocyclization of tertiary allylic alcohols

A variety of substituted 1-oxaspiro[4.5]dec-6-ene and 1-oxaspiro[5.5]undec-7-ene systems have been prepared by utilizing Amberlyst-15-catalyzed SN2′ oxaspirocyclizations under mild reaction conditions (−20°C) in quantitative yields. In this process, a tertiary allylic alcohol serves as the precursor of π-allylic carbocation and the primary, secondary or tertiary alcohol within the same molecule serves as the nucleophile.