2-((2-(1.Lambda.~5~-Diazenylidene)-3-oxobutanoyl)oxy)ethyl 2-(1.lambda.~5~-diazenylidene)-3-oxobutanoate AIDS-143109 AIDS143109 Butanoic acid, 2-diazo-3-oxo-, 1,2-ethanediyl ester NSC662779