Abstract
1) Heating of N-(2-hydroxyethyl)-1, 3-propylenediamine and N-methyl-N-(2-hydroxyethyl)-1, 3-propylenediamine in an autoclave, in the presence of a dehydration catalyst, afforded the seven-membered ring compounds, homopiperazine (yield, 11-15%) and N-methylhomopiperazine (yield, 13.3%), respectively. Dehydrative cyclization of N-(2-hydroxyethyl)-1, 3-propylenediamine by fusion of hydrohalide gave homopiperazine in 10.5-17% yield in the case of hydrochloride and 17-27.5% in the case of hydrobromide. In the case of N-alkyl-N-(2-hydroxyethyl)-1, 3-propylenediamine, the reaction was accompanied by liberation of the alkyl group and only homopiperazine was obtained.
2) Reaction of trimethylenediamine and ethylene glycol in dioxane, in the presence of Raney nickel, in an autoclave, afforded homopiperazine in 10% yield, except in the case of ethylenediamine and trimethylene glycol.
