Synthesis of 1,2,4‐oxadiazines and their rearrangement to pyrimidines

Abstract

Abstract Several amide oximes underwent condensation reactions with dimethyl acetylene dicarboxylate to afford 1:1 adducts. Under basic conditions, these adducts underwent ring closure to afford several methyl [3‐(substituted)‐4,5‐dihydro‐5‐oxo‐6 H ‐1,2,4‐oxadiazin‐6‐ylidene]acetates. The reactions of these compounds with a variety of amines resulted in addition‐rearrangement reactions with the formation of the corresponding methyl 2‐substituted‐5‐substituted amino‐1,6‐dihydro‐6‐oxo‐4‐pyrimidine carboxylates.