3-Bromopentadienylsilane:  A New Reagent for the Introduction of a Functional Pentadienyl Unit with Fixed Configuration

Abstract

The (Z)-1-trimethylsilyl-3-bromopenta-2,4-diene 3 was prepared through a sequence involving the reductive silylation of butadiene, dibromocarbene addition on the resulting disilane 1, and thermolytic ring opening. With aldehydes, this new pentadienylsilane reacts exclusively via an S(E)' ' pathway. In the presence of an alcohol or a carbamate under Lewis acid activation, 3 yields, respectively, bromopentadienyl ethers or bromopentadienyl-protected amines.