While the solvent-free reactions of the 2-benzoselenopyrylium salts (9) with methyl- or phenylhydrazine afforded the 1-hydrazino-1H-isoselenochromenes (11, 12), the treatment of the salts (9) with anhydrous hydrazine in dry acetonitrile resulted in a ring transformation to give the 5H-2,3-benzodiazepines (13) in one-pot under mild conditions in moderate yields.
