Nitrosation of methyl 2‐acylamino‐3‐dimethylaminopropenoates. A simple conversion of n ‐acylglycines into 5‐substituted 1,2,4‐Oxadiazole‐3‐carboxylates

A novel simple synthesis of 5‐substituted‐1,2,4‐oxadiazole‐3‐carboxylates 5 from N ‐acylglycines 1 , which are transformed with DMF in the presence of phosphorus oxychloride into 2‐substituted‐4‐dimethyl‐aminomethyleneoxazol‐5(4 H )‐ones 2 , followed by opening into 2‐aroylamino‐3‐dimethylamino‐propenoates 3 , and nitrosation to give the oximes 4 as intermediates, which cyclize spontaneously into 5‐substituted‐1,2,4‐oxadiazole‐3‐carboxylates 5 . The compounds 2 can be transformed into 5 without isolation of 3 and 4 .