Some observations on the stereochemical and regiochemical outcome of hydrostannylation of substituted propargyl alcohols

A regio- and stereocontrolled hydrostannylation of substituted propargyl alcohols and derivatives has been performed. Tri-n-butylstannyl hydride reacts with different substituted propargyl alcohols to give a mixture of Z/E isomers of vinylstannane with the stannyl moiety bonded to the carbon closest to the OH or OR group. A careful study of the reaction conditions allowed the preparation and isolation of pure Z isomer for a wide set of compounds. The reaction products are unstable under the conditions of preparation. An outline of the possible mechanism of the reaction is described.