Cyclic guanidines. V. Synthesis of hypoglycemic 2,2- and 3,3-diphenylimidazo[1,2-.ALPHA.][1,3]diazacycloalkane derivatives.

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Abstract
2,2- and 3,3-Diphenylimidazo[1,2-a][1,3]diazacycloalkane derivatives (4) and (5) were synthesized. The cyclization of 2-(.omega.-chloroalkylimino)-4,4-diphenylimidazolidines (3) resulted in a mixture of 4 and 5 in low yield. 5,5-Diphenylhydantoin (6) was alkylated at the N3 or O2 position and reduction of the remained carbonyl group of the products was successful. The 3-N-alkylated compounds (14) prepared from 6 selectively gave 4. The 2-o-ethyl derivative afforded 2-(.omega.-chloroalkylimino)derivatives (21). Heating 21 gave 2-oxo-bicyclic guanidines (22), and sodium hydride treatment of 21 gave 3-oxo-bicyclic guanidines (17) in good yield, respectively. Sodium bis(2-methoxyethoxy) aluminium hydride reduction of 17 and 22, having a carbonyl group in the molecule, gave 4 and 5, respectively. Under the same conditions, N-methyl-2-oxo- or 3-oxo-bicyclic guanidines and another compound (28) gave partially reduced products. The bicyclic guanidines (4) and (5) showed potent hypoglycemic activity in rats.