A new facet of the reaction of nitro heteroaromatic compounds with ethyl isocyanoacetate

Abstract

Nitre heteroarenes react with ethyl isocyanoacetate in the presence of 1,8-diazabicyclo[5.4.0]undecene (DBU) to give pyrroles or pyrimidine N-oxide depending on the structure of the starting nitro compounds. For example, 4-nitro-2,1,3-benzothiadiazole 3a reacted with ethyl isocyanoacetate to give ethyl 2,1,3-benzothiadiazole[3,4-c]pyrrole-2-carboxylate 4a (33%), while a similar reaction with 5-nitro-2,1,3-benzothiadiazole 3b gave the corresponding compound 4b (21%) as a sole product. A plausible mechanism for these reactions is presented.