Formaldehyde → 9-(2-cyclohexylethyl)-2,3,4,9-tetrahydro-2,6-dimethyl-1H-pyrido[3,4-b]indole

Participants

Reaction Conditions

Reaction Steps

2-(1-(2-cyclohexylethyl)-5-methyl-1H-indol-3-yl)-N-methylethanamine (72 mg, 0.23 mmol) was dissolved in acetonitrile (2 mL) containing 5% TFA and the reaction mixture was refluxed. 37% aqueous formaldehyde (0.02 mL) was added to the reaction mixture and refluxed for additional 2 h, cooled to 25° C., concentrated under reduced pressure and partitioned between ethyl acetate and saturated aqueous NaHCO3. The organic layer was dried over sodium sulfate, evaporated under reduced pressure and the residue was purified by silica gel chromatography (eluent EtOAc/EtOH/NH3: 9/1/0.1) to obtain 9-(2-cyclohexylethyl)-2,3,4,9-tetrahydro-2,6-dimethyl-1H-pyrido[3,4-b]indole (52 mg). The free base was converted into its oxalate salt by treatment of oxalic acid (1 equiv) in anhydrous THF. 1H NMR (DMSO): 7.5 (d, 1H), 7.4 (s, 1H), 6.9 (d, 1H), 4.3 (bs, 2H), 4.0 (t, 2H), 3.6 (bs, 2H), 2.8 (m, 5H), 2.3 (s, 3H), 1.8-0.7 (m, 13H).

Provenance & Evidence