Abstract
Various methods were attempted to synthesize (1-adamantyl) guanidine (1) and 1- (1-adamantyl) -3-aminoguanidine (2) from 1-aminoadamantane. It was found that (1) is prepared by heating a mixture of 1-aminoadamantane, its hydrochloride and cyanamide at 120°C, and that (2) is obtained by reacting 1- (1-adamantyl) -S-methylisothiourea (3) hydriodide with anhydrous hydrazine in absolute ethanol. The latter reaction was inferred to occur by addition of hydrazine to (3), followed by elimination of methyl mercaptane.
Treatment of (1) with conc. HCl gave guanidine hydrochloride and 1-adamantyl chloride. This reaction was different from that of usual N-substituted guanidine. Treatment of t-butylguanidine similarly gave guanidine hydrochloride and t-butyl chloride. Thus, it was inferred that this abnormal fission is due to the presence of a tertiary carbon atom, which easily forms carbonium ion.
