5.6.7.8- tetrahydroquinoxaline

Hydrogenation of quinoxaline, or 1,2,3,4-tetrahydroquinoxaline, over a 5% rhodium-on-alumina catalyst at 100°C and 136 atm, or over... 

Each quaternary 1 -(2-hydroxyethyl)-2,3-dihydro-1,4-ethanoquinoxalin-1 -ium halide (553, X = Cl, Br, or I) underwent thermolysis to give the corresponding 1 -(2-halogenoethyl)-4-(2-hydroxyethyl)-1,2,3,4-tetrahydroquinoxaline... 

Methylquinoxaline with phenyUithium gave a separable mixture of 2-methyl-3-phenylquinoxaline (45), 2-methyl-3-phenyl-3,4-dihydroquinoxaline (46), and 2-methyl-2,3-diphenyl-1,2,3,4-tetrahydroquinoxaline (47) [PhLi (made in situ), Et20, <20°C, 90 min 20%, 45%, and 35%, respectively). 

Methyl-1,2,3,4-tetrahydroquinoxaline (161) gave 1-methyl-4-[A -phenyl(thio-carbamoyl)]-l,2,3,4-tetrahydroquinoxaline (162) (PhNCS, CH2CI2, reflux, 1 h 30%). ... 

Quinoxahne gave 1,2,3,4-tetrahydroquinoxalme (NiCl2-6H20, MeOH, NaBHrl, <20°C, 1 h 58%) 2-methyl- and 2,3-dimethyl-1,2,3,4-tetrahydroquinoxaline were produced similarly (52% and 92%, respectively).589 The 2-pyrimidin-amine BH3 complex any also be so used.199... 

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