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(4H)‐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.