One-pot synthesis of 2,7-dioxabicyclo[2.2.1]heptanes from oxoallylsilanes

摘要

A one-pot high-yielding synthesis of silylated 2,7-dioxabicyclo[2.2.1] heptanes from oxoallylsilanes is described. The mechanism of this tandem reaction is a sequential epoxidation of the allylsilane moiety and subsequent intramolecular cyclization. This simple protocol allows the synthesis of epoxy-bridged tetrahydropyrans from allene in two high-yielding steps: silylcupration of allene (followed by capture of the intermediate cuprate with enones) and treatment of the oxoallylsilanes thus obtained with MCPBA. However, under the same conditions, oxovinylsilanes yielded epoxysilyl ketones in a very stereoselective manner.