Preparation and Chemistry of Δ⁸-Hexahydro-1,4,8-Pyrimidazole, Δ⁹-1,5,9-Triazabicyclo(4.4.0)decene, and Δ⁹-1,4,9-Triazabicyglo(5.3.0)decene

The preparations of Δ 8 -hexahydro-1,4,8-pyrimidazole, Δ 9 -1,5,9-triazabicyclo(4.4.0)decene, and Δ 9 -1,4,9-triazabicyclo(5.3.0)decene from the corresponding 2-(ω-hydroxyalkylamino)-Δ 2 -1,3-diazacycloalkenes by chlorination and dehydrohalogenation are described. The nitro derivatives of these bicyclic compounds are more stable towards refluxing ethanol than 1-nitro-2,3,5,6-tetrahydro-1-imidaz(1,2-a)imidazole.