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 (6.22 g, 20 mmol) and dimethyl acetylenedicarboxylate (4.26 g, 30 mmol) in acetic anhydride (50 mL) was heated at 60-70° C. for 3.5 hours. The reaction mixture was then cooled to room temperature and then evaporated under reduced pressure to dryness. The solid residue was recrystallized from ethanol to give 3-methyl-5,10-dihydropyrrolo[1,2-b]isoquinoline-1,2-dicarboxylic acid dimethyl ester 7.38 g, (94.4%); mp 155-158° C.; 1H NMR (DMSO-d6) δ δ 3.70 (3H, s, OMe), 3.86 (3H, s, COOMe), 3.89 (3H, s, COOMe), 4.41 (2H, s, CH2), 4.86 (2H, s, CH2), 7.01 (2H, d, J=8.5 Hz, ArH), 7.12 (1H, m, ArH), 7.22-7.25 (1H, m, ArH), 7.30-7.32 (1H, m, ArH), 7.37 (2H, d, J=8.5 Hz, ArH), 7.37-7.38 (1H, m, ArH); m/z 391.0 (M+H)+ Anal. Calcld. for C23H21NO5. 0.1H2O: C, 70.25; H, 5.43; N, 3.56. Found: C, 70.15; H, 5.44; N, 3.49.

Provenance & Evidence