Arbeiten über Phosphorsäure‐ und Thiophosphorsäure‐ester mit einem heterocyclischen Substituenten. 6. Mitteilung . 3‐Acyl‐thio‐ und ‐dithio‐carbazinsäure‐alkylester und 2′‐(Dialkoxy‐phosphinothioyl)‐carbonsäurehydrazide sowie deren Ringschluss zu 3‐Acyl‐5‐alkoxy‐ und ‐5‐alkylthio‐1,3,4‐thiadiazol‐2(3 H )‐onen bzw. 3‐(Dialkoxy‐phosphinothioyl)‐5‐substit.‐1,3,4‐oxadiazol‐2(3 H )‐onen

Thio‐ and dithio‐carbazic acid alkyl esters, acylated in position 3 by radicals of carboxylic, sulfonic, phosphoric, thiophosphoric or thiophosphonic acids, undergo spontaneous ring closure with phosgene, in absence of any acid binding agent, to form the corresponding 3‐acyl‐5‐alkoxy‐ and ‐5‐alkylthio‐l,3,4‐thiadiazol‐2(3 H )‐ones. Similarly 3‐thiophosphorylated 5‐substituted 1,3,4‐oxadiazol‐2(3 H )‐ones can be prepared from carboxylic acid hydrazides acylated by thiophosphoric acid radicals. In the latter case, however, a stoichiometric amount of pyridine is necessary to avoid cleavage of the PN‐bonding.