DIAZABICYCLOALKANES WITH NITROGEN ATOMS IN THE NODAL POSITIONS. 9. INTRAMOLECULAR CYCLIZATION OF N-(γ-BROMOPROPYL)-TETRAHYDROQUINOXALINES AND BEHAVIOR OF BENZO-1,5-DIAZABICYCLONONENE IN HYDROBROMIC ACID

Article abstract of DOI:10.1007/BF00514468

The introduction of an N,N'-trimethylene bridge in the tetrahydroquinoxaline molecule is complicated by cyclization of γ-bromopropyl derivatives of tetrahydroquinoxaline at the carbon atom of the aromatic ring.The reaction of N-R-tetrahydroquinoxalines (R = H, COCH3) which 1,3-dibromopropane leads to products of cyclization at the aromatic ring (1,2,3,5,6,8,9,10-octahydropyrazino<1,2,3,4-l,m,n><1,10>phenanthroline and N-acetyl-1,2,6,7-tetrahydro-3H,5H-pyrido<1,2,3-d,e>quinoxaline) and to an N-alkylation product .Benzo-1,5-diazabicyclo<3.2.2>nonene is formed in only trace amounts in the cyclization of N-(γ-bromopropyl) tetrahydroquinoxaline and upon heating in HBr can be isomerized with migration of the trimethylene bridge to the aromatic ring.