Reactions of Chlordiazepoxide and Diazepam N-Oxide with Dimethyl Acetylenedicarboxylate with Rearrangement to Quinoxaline Derivatives and X-Ray Analysis of a Resultant Tetracyclic Compound

Abstract

Three 1, 4-benzodiazepine N-oxides, diazepam N-oxide (IIIa), nordiazepam N-oxide (IIIb) and chlordiazepoxide (IV) were submitted to 1, 3-dipolar cycloaddition reaction with dimethyl acetylenedicarboxylate to give quinoxaline derivatives (Va from IIIa ; Vb from IIIb ; XI and XII from IV). It is likely that the cycloaddition reactions involve the rearrangement of Beckmann type in which initially formed adducts (i.e., VIa) rearrange to quinoxaline derivatives (i.e., VIIa). The structural determination of XII was made by X-ray crystallographic analysis.