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 carbonyl compounds in the presence of triethyl amine occurs with formation of the Schiff s base and intramolecular hydrolysis of the adjacent cyano group to give the alkylideneamino derivatives 8a‐f . When the α‐carbon of the ketone has at least one proton, the prolonged contact of 8a‐f with triethylamine 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 pyrrolo4,3‐b]1,4]diazepines 9 . If a strong base is used the first ring to be formed is the pyrrole ring as evidenced in the reaction of 8a with 1,8‐diazabicyclo5.4.0]undec‐7‐ene leading to 14 . The subsequent addition of methyl amine to the reaction mixture, caused cleavage of the alkylideneamino unit and formation of the amidine function from the imi date ( 15 ). The addition of acid to the imidates 8a and 8f led to the diazepine compounds 10a and 10f respectively. A suspension of compound 8e in ethanol and triethylamine evolved to a pyrazinone structure 12 under kinetic conditions (4 hours, room temperature) and to the pyrrolo4,3‐b]1,4]diazepine 9e under thermodynamic conditions (48 hours, room temperature).