Dimethyl acetylenedicarboxylate → Pyrrolo(1,2-b)isoquinoline-1,2-dicarboxylic acid, 5,10-dihydro-3-methyl-, dimethyl ester

Participants

Reaction Conditions

Reaction Steps

A mixture of 2-acetyl-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (3.00 g, 13.6 mmol) and dimethyl acetylenedicarboxylate (2.84 g, 20 mmol) in acetic anhydride (25 mL) was heated at 65-70° C. for 1.5 hours. The reaction mixture was then cooled and evaporated under reduced pressure to dryness. The residue was recrystallized from methanol to give 3-methyl-5,10-dihydropyrrolo[1,2-b]-isoquinoline-1,2-dicarboxylic acid dimethyl ester, 3.29 g, (80.2%); mp 152-154° C.; 1H NMR (DMSO-d6) δ 2.40 (3H, s, Me), 3.70 (3H, s, COOMe), 3.72 (3H, s, COOMe), 4.18 (2H, s, CH2), 5.06 (2H, s, CH2), 7.29-7.32 (2H, m, 2×ArH), 7.35-7.39 (2H, m, 2×ArH); m/z 299.0 (M+H)+. Anal. Calcld. for C17H17NO4: C, 68.22; H, 5.72; N, 4.68. Found: C, 68.29; H, 5.77; N, 4.67.

Provenance & Evidence