Studies on organophosphorus compounds XXII The dimer of <i>p</i>‐methoxyphenylthionophosphine sulfide as thiation reagent. a new route to O‐substituted thioesters and dithioesters

Abstract

Abstract Simple alifatic and aromatic esters, such as ethyl, iso‐propyl, and benzyl benzoates, benzyl butanoate, ethyl heptanoate, and ethyl 1‐ and 2‐naphthoate, respectively, react with the dimer of p ‐methoxyphenylthiono‐phosphine sulfide 1 in anhydrous xylene at 140°C to give the corresponding 0‐substituted thioesters in nearly quantitative yields. Also simple alifatic and aromatic S‐substituted thioesters, such as S‐phenyl, S‐benzyl and S‐tert‐butyl thiobenzoates, S‐phenyl and S‐benzyl thioacetates, and S‐ethyl thiobutanoate, produced the corresponding dithioesters in nearly quantitative yields upon treatment with 1 in anhydrous toluene at 110°C. 13 C NMR data for the carbonyl‐ and corresponding thiocarbonyl carbons, have been recorded and a linear relation between the chemical shifts of CS and CO is found: δ(CS) = 1.75·δ (CO) ‐ 79.6 for 0‐substituted thioesters and δ(CS) = 1.31.δ (CO) ‐ 22.1 for dithioesters. An anomalous reaction has been observed: Thiobenzoic acid, S,S'‐methylene ester 2 reacted with 1 to give 4,5‐diphenyl‐1‐1,3‐dithiol‐2‐thion 3.