Pyrrolidine → 5-(4-Methylpiperazin-1-yl)-1H-indole

Participants

Reaction Conditions

Reaction Steps

A solution of 1-methyl-4-(3-methyl-4-nitro-phenyl)-piperazine (10a), (2.63 g, 11.2 mmol), N,N-dimethylformamide dimethyl acetal (4.7 mL, 35.84 mmol) and pyrrolidine (1.5 mL, 17.9 mmol) in anhydrous N,N-dimethylformamide (20 mL) was heated at 120° C. for 18 hours. The reaction mixture was concentrated in vacuo, taken up in ethanol (50 mL) containing 2 mL of water and to this was added ammonium formate (3.67 g, 58.2 mmol). Palladium, 10 wt. % on activated carbon (0.84 g) was added and the suspension was stirred and heated at 50° C. for 30 minutes. The reaction mixture was then filtered through a celite pad and the pad rinsed with hot methanol (20 mL). The combined filtrate and washings were concentrated in vacuo and the residue was taken up in ethyl acetate (100 mL), washed with aqueous saturated sodium bicarbonate solution (2×100 mL), brine, dried (MgSO4) and concentrated in vacuo. The resultant crude product was purified by flash chromatography on SiO2 eluting first with hexane and then 15% ethyl acetate/hexane to afford the desired title compound as an off-white solid, 1.44 g, 60%.

Provenance & Evidence