Ammonia → tert-Butyl 4-((1-methyl-1H-imidazol-4-yl)methyl)piperazine-1-carboxylate

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Reaction Steps

N-Boc-piperazine (0.470 g, 2.50 mmol, 1.1 eq) was dissolved in DCM (6.2 mL). To this solution, 1-methyl-1H-imidazole-4-carboxaldehyde (0.250 g, 2.27 mmol, 1 eq) was added followed by chlorotitanium triisopropoxide (1.19 mL, 5.0 mmol, 2.2 eq). The resulting solution was stirred at room temperature for 10 min before the addition of sodium triacetoxyborohydride (2.40 g, 11.3 mmol, 5 eq). The mixture was stirred at room temperature for 17 h and was diluted with EtOAc (12 mL). It was then poured into ammonia (35% sol. in H2O, 6 mL) and the resulting mixture filtered and washed with EtOAc. The organic phase was washed with H2O dried (MgSO4) and the solvent removed in vacuo. The crude material was purified by column chromatography on a Biotage SP1 system eluting with methanol (1-8%) in dichloromethane to give the title compound as a clear oil (0.390 g, 62%); 1H-NMR (500 MHz, CDCl3): δ 1.46 (s, 9H, C(CH3)3), 2.48 (t, J=5.0 Hz, 4H, piperazine N(CH2)2), 3.45 (t, J=5.0 Hz, 4H, piperazine N(CH2)2), 3.52 (s, 2H, NCH2), 3.66 (s, 3H, imidazole Me), 6.80 (s, 1H, imidazole 5-H), 7.38 (s, 1H, imidazole 2-H); LC (Method B)-MS (ESI, m/z): 281 [(M+H+)].

Provenance & Evidence