Enamines from formamides. Synthesis of 1,2,3,4-tetrahydro-1-substituted β-carbolines

Abstract

RAHUL VOHRA and DAVID B. MACLEAN. Can. J. Chem. 72, 1660Chem. 72, (1994.Pyridines and benzopyridines substituted with trimethylsilylmethyl groups, a or y to the nitrogen atom, have been found to react with formamides by way of a Peterson reaction to form enamines. Trimethylsilylmethylbenzene behaved similarly. The enamines prepared from Nb-formy]-M',Nb-dimethyltryptamine cyclized readily to P-carbolines. The reaction of formamides with lithiated 4-methylpyridines as a route to enamines was examined but proved to be less general and proceeded in lower yield than the route by way of the Peterson reaction. The nuclear magnetic resonance and mass spectra of the enamines and P-carbolines derived from 3 are discussed.RAHUL VOHRA et DAVID B. MACLEAN. Can. J. Chem. 72, 1660 (1994).On a trouvC que les pyridines et benzopyridines substituies par des groupes trimCthylsilylmCthyles en CY ou en y de I'azote rCagissent avec les formamides, par le biais d'une reaction de Peterson, pour conduire h la formation dlCnamines. Le trimCthy1-silylmCthylbenzi?ne se comporte de la mzme manicre. Les Cnamines prCparCes partir de la Nb-formy]-Na,Nb-dimethyltryptamine se cyclisent facilement en P-carbolines. On a examin6 la rkaction des formamides avec les 4-mtthylpyridines lithiCes, comme voie d'acccs aux Cnamines, mais on a montrk que la rkaction est moins gCnCrale et qu'elle se produit avec un rendement plus faible que la voie impliquant la reaction de Peterson. On discute des spectres de rCsonance magnCtique nuclkaire et de masse des Cnamines et des P-carbolines dCrivCs du produit 3.[Traduit par la rkdaction]

Sequential One-Pot Vilsmeier–Haack and Organocatalyzed Mannich Cyclizations to Functionalized Benzoindolizidines and Benzoquinolizidines

“…Water was added and the usual work-up (EtOAc) and purification (50–80% EtOAc in hexanes) afforded 20 (206 mg, 96%) as an orange oil. Analytical data were in accordance with those reported in the literature …”

“…Analytical data were in accordance with those reported in the literature. 21 1 H NMR (300 MHz, CDCl 3 ) 1:0.6 mixture of rotamers: δ (ppm) 7.90 (s) and 7.70 (s) (1H, rotamers), 6.71−6.55 (m, 3H), 3.76 (s) and 3.75 (s) (3H, rotamers), 3.74 (s, 3H), 3.44 (t) and 3.34 (t) (J = 7.0 Hz, 2H, rotamers), 2.78 (s) and 2.75 (s) (3H, rotamers), 2.72−2.65 (m, 2H). 13 7 (q), 55.6 (q), 51.1 (t), 45.7 (t), 34.8 (q), 34.2 (t), 32.5 (t), 29.5 (q).…”

“…Iminium Ion (21). Following the procedure used to prepare 18a, 13 was treated with triflic anhydride and DTBMP in CDCl 3 .…”