Dimethyl acetylenedicarboxylate → 3-(3,4-Difluorophenyl)-5,10-dihydropyrrolo[1,2-b]isoquinoline-1,2-dicarboxylic acid dimethyl ester

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Reaction Conditions

Reaction Steps

A mixture of 2-(3,4-difluorobenzoyl)-1,2,3,4-tetrahydro-isoquinoline-3-carboxylic acid (11.10 g, 35 mmol) and dimethyl acetylenedicarboxylate (7.39 g, 52 mmol) in acetic anhydride (70 mL) was heated at 60-70° C. for 15 min. The reaction mixture was then cooled and evaporated in vacuo to dryness. The solid residue was recrystallized from ethanol to give 3-(3,4-difluorophenyl)-5,10-dihydropyrrolo[1,2-b]isoquinoline-1,2-dicarboxylic acid dimethyl ester 10.97 g, (78.6%); mp 142-144° C.; 1H NMR (DMSO-d6) δ 3.61 (3H, s, Me), 3.77 (3H, s, Me), 4.31 (2H, s, CH2), 5.00 (2H, s, CH2), 7.21-7.27 (1H, m, ArH), 7.29-7.35 (3H, m, 3×ArH), 7.37-7.43 (1H, m, ArH), 7.50-7.65 (2H, m, 2×ArH); m/z 397.00 (M+H)+ Anal. Calcld. for C22H17F2NO4: C, 66.50; H, 4.31; N, 3.52. Found: C, 66.65; H, 4.51; N, 3.47.

Provenance & Evidence