Three-component reaction between secondary phosphine sulfides, elemental selenium and vinyl ethers: the first examples of Markovnikov addition of thioselenophosphinic acids to double bond

Thioselenophosphinic acids, R2P(Se)SH, generated in situ from secondary phosphine sulfides and elemental selenium, easily add to various vinyl ethers (equimolar ratio, 100 °C, 1,4-dioxane, up to 40 min) to give earlier unknown S- and Se-[1-(organyloxy)ethyl]thioselenophosphinates, i.e., R2P(Se)SCH(Me)OR′ and R2P(S)SeCH(Me)OR′ (R, R′=alkyl, aralkyl, hetaralkyl and aryl), the S-esters being predominant (73–95% total yield).