Synthesis and Rearrangement of Silylated Oxy- Cope Systems

Abstract

Addition of allyl or vinyl organometallic reagents to chiral a,b- or b,g-unsaturated acylsilanes afforded stereoselectively 3-silylated 3-hydroxy-1,5-dienes that are stereoselectively converted to d,e-unsaturated acylsilanes by the thermal oxy-Cope rearrangement. The rearrangement is restricted to compounds possessing an (alkoxy)methyl substituent at the silicon moiety; upon heating, analogous compounds with the t-BuMe2Si group in the 3-position led to decomposition only. The (alkoxy)methyl group at silicon is supposed to act as a weak internal base, which accelerates the rearrangment reaction.