Ring Opening of Epoxides by Pendant Silanols

Abstract

We present a new ring-opening reaction of epoxides by pendant silanols, catalyzed by either Ph₃C⁺BF₄^- or BINOL-phosphoric acid. Silanol epoxides derived from <i>trans</i>-allylic alcohols, <i>cis</i>-allylic alcohols, <i>trans</i>-homoallylic alcohols, and <i>cis</i>-homoallylic alcohols were all compatible and gave products from either <i>endo</i>- or <i>exo</i>-ring opening. With silanol epoxides derived from 4-alkenyl silanols, an unusual rearrangement to tetrahydrofuran products was observed. The utility of this methodology was demonstrated in a short preparation of protected d-arabitol.