Extraordinary sulfur/oxygen exchange between P=S and C=O bonds during the reaction of γ-amino ynones ketones with secondary phosphine sulfides

Unknown reactivity patterns of P=S and C=O bonds were observed when γ-amino α, β-ynones reacted with secondary phosphine sulfides affording, instead of the addition/ cyclization products, 1,2-dihydro-3H-pyrrole-3-thiones and the corresponding secondary phosphine oxides. The reaction mechanism involves the sulfur/oxygen exchange between the P=S and C=O functions. This is the first case of the successful competition between the P=S and P–H moieties as nucleophiles for electrophilic triple bond.