Synthetic approaches to komarovispiranes. Enantiospecific synthesis of bicyclo[3.3.0]octanespiro[3.1′]cyclohexanes

A ring-closing metathesis based spiroannulation of cyclopentane and cyclohexanes at the C-3 carbon atom of a bicyclo[3.3.0]octane, as a model study directed towards the enantiospecific synthesis of the novel diterpenes komarovispiranes, is described.