Reactivity studies of ethyl(Z)-N-(2-amino-1,2-dicyanovinyl) formimidate with carbonyl compounds in the presence of base

The reaction of ethyl(Z)-N-(2-amino-1,2-dicyanovinyl)formimidate 6 with car bonyl compounds in the presence of triethylamine occurs with formation of t he Schiffs base and intramolecular hydrolysis of the adjacent cyano group t o give the alkylideneamino derivatives 8a-f. When the alpha -carbon of the ketone has at least one proton, the prolonged contact of 8a-f with triethyl amine causes intramolecular cyclization between this carbon and the imidate carbon atom to form a seven membered ring. This is followed by cyclization of the cyano and amido groups, leading to the pyrrolo[4,3-b][1,4]diazepine s 9. If a strong base is used the first ring to be formed is the pyrrole ri ng as evidenced in the reaction of 8a with 1,8-diazabicyclo[5.4.0]undee-7-e ne leading to 14. The subsequent addition of methyl amine to the reaction m ixture, caused cleavage of the alkylideneamino unit and formation of the am idine function from the imidate (15). The addition of acid to the imidates 8a and 8f led to the diazepine compounds 10a and 10f respectively. A suspen sion of compound 8e in ethanol and triethylamine evolved to a pyrazinone st ructure 12 under kinetic conditions (4 hours, room temperature) and to the pyrrolo[4,3-b][1,4]diazepine 9e under thermodynamic conditions (48 hours, r oom temperature).