Stereoselective access to functionalized β-γ unsaturated acids

Stereoselective synthesis of vinylstannanes bearing a carboxylic acid function was achieved from β-γ alkynoic acids via hydrostannation, stannylcupration or silastannation reactions. Regioselectivity is highly dependent on the nature of the stannylanions used and on protection of the carboxylic acid function.