A SHORT AND CONVENIENT SYNTHESIS OF NOVEL THIENOPYRAZOLODIAZEPINE AND THIENOPYRAZOLOXAZEPINE SKELETONS VIA NITRILIMINE CYCLOADDITION

摘要

Silver carbonate treatment of 3-thenyl-substituted hydrazonoyl chloride (3) promoted the in situ generation of the corresponding nitrilimine (4) which constitute the key intermediate in the three step synthesis of both thieno[2,3-f]pyrazolo[1,5-a][1,4]diazepine and thieno[2,3-f]yrazolo[1,5-a][1,4]-oxazepine skeletons. The concurrent formation of unusual pyridazine derivatives arising from the electrophilic attack of a nitrilium cation to the carbon-carbon double bond is also discussed in some detail.