Toward Enediyne Mimics: Methanolysis of Azoesters and a Bisazoester.
Enediyne anticancer antibiotics have attracted tremendous interest in the past decade. The inherent difficulty in synthesizing these structurally complex natural products with the strained enediyne moiety has motivated a search for simpler molecules that mimic enediyne chemistry. The ultimate objective is to identify molecules that produce 1,4-benzenoid diradicals, which are known to induce DNA cleavage in the natural products. Toward this goal, several aromatic azoesters have been synthesized, and EPR reveals the presence of radical intermediates in their methanolysis. A 1,4-bisazoester has also been synthesized, and its methanolysis products have been studied by reversed-phase HPLC. The formation of 1,2-dicyanobenzene from the 1,4-bisazoester is consistent with the existence of a 1,4-diradical intermediate.