SYNTHESIS OF 1-(PENTAFLUOROPHENYL)-β-CARBOLINE

Article abstract of DOI:10.1016/S0022-1139(00)82931-0

Thermal condensation of tryptamine with pentafluorobenzaldehyde in ethanol afforded 1-(pentafluorophenyl)-1,2,3,4-tetrahydro-β-carboline (I, 51percent yield), together with two byproducts (IIa, 9percent yield and IIb, 14percent yield) which were produced by nucleophilic substitution of an aromatic fluorine atom by the tryptamine amino group.In solvent acetic acid, the same reactants gave 2-acetyl-1-(pentafluorophenyl)-1,2,3,4-tetrahydro-β-carboline (III, 64percent yield) as the main product, together with a reduced yield (20percent) of I.Dehydrogenation of I with selenium dioxide provided 1-(pentafluorophenyl)-β-carboline (IV) in 84percent yield; III also gave IV in 72percentyield.Partial dehydrogenation of I with potassium permanganate provided 1-(pentafluorophenyl)-3,4-dihydro-β-carboline (V, 80percent yield) but V could not be obtained from III.Indole itself provided (pentafluorophenyl)bis(3-indolyl)methane (VI, 82percent yield) by simple reflux with pentafluorobenzaldehyde in propanol.In solvent acetic acid, the yield of VI was 78percent.