Sir: In spite of its potential importance there is still no generalized method for the direct preparation of thiol es- ters from carboxylic acids and thio1s.l We now wish to re- port this transformation, which involves treatment of a car- boxylic acid and a thiol with diethyl phosphorocyanidate (DEPC)2 or diphenyl phosphorazidate (DPPA)3 in the presence of triethylamine in dimethylformamide solution. While optimum reaction conditions have yet to be estab- lished, the results ...
