Abstract
Synthesis of 2, 2- and 3, 3-diphenylimidazo [1, 2-a] [1, 3] diazacycloalkane derivatives (4) and (5) was attempted. The cyclization of 2-(ω-chloroalkylimino)-4, 4-diphenylimidazolidines (3) was not advantageous because it gave a mixture of 4 and 5 in low yield. 5, 5-Diphenylhydantoin (6) was alkylated at the N3 or O2 position and successive reduction of the remained carbonyl group of the products resulted in success. The 3-N-alkylated compounds (14) prepared from 6 selectively gave 4. The 2-O-ethyl derivative (19) afforded 2-(ω-chloroalkylimino) derivatives (21). Heating 21 gave 2-oxo-bicyclic guanidines (22), and treatment of 21 with sodium hydride yielded 3-oxo-bicyclic guanidines (17) in good yield, respectively. Sodium bis (2-methoxyethoxy) aluminum 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 (18) and (28) gave partially reduced products. The bicyclic guanidines (4) and (5) showed potent hypoglycemic activity.
