2,4-Dimethoxybenzylamine → 7-bromo-2-(2,4-dimethoxybenzyl)-3,4-dihydropyrrolo[1,2-a]pyrazin-1(2H)-one

Participants

Reaction Conditions

Reaction Steps

(2,4-Dimethoxyphenyl)methanamine (Aldrich; 4.36 mL, 28.9 mmol) was added to a stirred solution of methyl 4-bromo-1-(2-bromoethyl)-1H-pyrrole-2-carboxylate (Example 165a; 3.60 g, 11.58 mmol) in DMSO (15 mL) at RT. The reaction was heated at 150° C. in an oil bath for 5 h. After it was cooled to RT, the brown mixture was partitioned between 10 mL of 2.0 N aq. HCl and 200 mL of EtOAc. The layers were separated; the organic solution was washed with 2.0 N aq. HCl (5 mL) followed by brine (5 mL), dried (Na2SO4), and concentrated. Purification on a silica gel column (25-75% EtOAc in Hexanes) gave 7-bromo-2-(2,4-dimethoxybenzyl)-3,4-dihydropyrrolo[1,2-a]pyrazin-1(2H)-one (3.61 g, 9.88 mmol, 85% yield) as an off-white crystalline solid. 1H NMR (400 MHz, DMSO-d6) δ ppm 7.15 (1H, d, J=1.8 Hz), 7.11 (1H, d, J=8.2 Hz), 6.68 (1H, d, J=1.8 Hz), 6.59 (1H, d, J=2.3 Hz), 6.50 (1H, dd, J=8.3, 2.4 Hz), 4.53 (2H, s), 4.12 (2H, dd, J=6.7, 5.2 Hz), 3.81 (3H, s), 3.76 (3H, s), 3.57 (2H, dd, J=6.7, 5.0 Hz). m/z (ESI, +ve) 365/367 (M+H)+.

Provenance & Evidence