A regioselective synthesis of isomeric 5-alkylthio-and 3-alkylthioisoro azoles 3 and 4 has been developed from acylketene dithioacelals 2. Thus the reaction of 2a—l with hydroxylamine hydrochloride in the presence of sodium methoxide in refluxing methanol afibrded 3-substituted 5-alkylthioisoxazoles 3a—l in good yields. When compounds 2a-l were reacted with hydroxylamine hydrochloride in the presence of sodium acetate/acetic ...