Reaction Steps
A mixture of 2,3,4,5-tetrahydro-2,8-dimethyl-5-(prop-2-ynyl)-1H-pyrido[4,3-b]indole[(p-tolylhydrazine hydrochloride (600 mg, 3.7 mmol), propargyl bromide (80 wt % solution in toluene, 0.34 mL, 3.7 mmol), triethyl amine (1.5 mL, 11.3 mmol) and N-methyl-4-piperidone hydrochloride (316 mg, 2.1 mmol) were taken in ethanol (15 mL) to obtain 80 mg of 2,3,4,5-tetrahydro-2,8-dimethyl-5-(prop-2-ynyl)-1H-pyrido[4,3-b]indole after purification on silica gel (230-400 mesh) chromatography eluting with MeOH-DCM gradient) (150 mg, 0.6 mmol)], 2-bromopyridine (0.06 mL, 0.6 mmol), dichlorobis(triphenylphosphine) palladium (8 mg, 0.012 mmol), CuI (1 mg, 0.006 mmol), and triethylamine (0.01 mL 0.071 mmol) in acetonitrile (5 mL) was heated at 80° C. for 1.5 h to obtain 108 mg of 2,3,4,5-tetrahydro-2,8-dimethyl-5-(3-(pyridin-2-yl)prop-2-ynyl)-1H-pyrido[4,3-b]indole after purification by reverse-phase chromatography (C-18, 500 mm×50 mm, Mobile Phase A=0.05% TFA in water, B=0.05% TFA in acetonitrile, Gradient: 10% B to 80% B in 30 min, injection vol. 5 mL). 1H NMR (DMSO-d6, TFA salt) δ (ppm): 8.45-8.40 (d, 1H), 7.80-7.70 (t, 1H), 7.45-7.40 (m, 1H), 7.30-7.25 (t, 1H), 7.25 (s, 2H), 7.10-7.00 (d, 1H), 5.60 (s, 2H), 4.60-4.55 (d, 1H), 4.25-4.20 (d, 2H), 3.85-3.75 (d, 1H), 3.65-3.40 (m, 2H), 3.00 (s, 3H), 2.30 (s, 3H).
