Cyclic Guanidines. I. Synthesis of Hypoglycemic 1-Substituted 2-Imino-1, 3-diazacycloalkanes

Abstract

Reaction of 2-benzylaminoethylamine (1a) with cyanogen bromide was investigated under various conditions to obtain desired 1-benzyl-2-iminoimidazolidine (2a) in quantitative yield. In addition, in the presence of base this reaction gave 3-carbamoyl derivative (3a) or 3-methoxyformimidoyl derivative (6) of 2a. The 3-carbamoyl group of 3a was rearranged to the 2-imino group on heating to give 2-carbamoylimino derivative (5a). On the other hand, 6 was derived to 3a or 3-methoxycarbonyl derivative (7) by heating under strong or mild acidic medium, respectively. 3-Amidino-1-benzyl-2-iminoimidazolidine (9) was prepared through 2-benzylaminoethylguanidine (8) from 1a. 1-Benzyl- or 1-benzhydryl-2-cyanoimino-1, 3-diazacycloalkanes (10) having five-, six- and seven-membered ring size were obtained on heating of 1 with dimethyl cyanoimidodithiocarbonate and then the cyano group of 10 was selectively removed to yield 1-benzyl- or 1-benzhydryl-2-imino-1, 3-diazacycloalkanes (2). Some of 1-substituted 2-imino-1, 3-diazacycloalkane derivatives showed hypoglycemic activity.