Dimethyl Δ³-1,2-diazetine-1,2-dicarboxylate: a new four-membered 6π-ring system

Abstract

Dimethyl Δ3-1,2-diazetine-1,2-dicarboxylate has been prepared by photolysis of the 1 : 1 adduct of 2,5-dimethyl-3,4-diphenylcylopenta-2,4-dienone and 2,3-dimethoxycarbonyl-2,3-diazabicyclo[2,2,0]hex-5-ene; this new ring system formally satisfies the Hückel (4n+ 2) rule, but no pronounced stability was observed, and the absence of a ring current suggests that it is not aromatic by this criterion.