Abstract
The thioselenophosphinic acids, R2P(Se)SH (R = Ph, Cy, aralkyl), prepared by acidification of the sodium salts or generated in situ by reaction of secondary phosphine sulfides with elemental selenium, add easily to diverse vinyl sulfides and vinyl selenides in a Markovnikov manner to give the corresponding S- and Se-esters in a ∼60:40 molar ratio (83–96% total yield).