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

HRID 1958520Notes

Reaction equation

[C:1]([N:4]1[CH:13](C(O)=O)[CH2:12][C:11]2[C:6](=[CH:7][CH:8]=[CH:9][CH:10]=2)[CH2:5]1)(=O)[CH3:2].[C:17]([C:23]([O:25][CH3:26])=[O:24])#[C:18][C:19]([O:21][CH3:22])=[O:20]>C(OC(=O)C)(=O)C>[CH3:22][O:21][C:19]([C:18]1[C:17]([C:23]([O:25][CH3:26])=[O:24])=[C:1]([CH3:2])[N:4]2[C:13]=1[CH2:12][C:11]1[CH:10]=[CH:9][CH:8]=[CH:7][C:6]=1[CH2:5]2)=[O:20]

Participants

Conditions

Temperature: 67.5 °C

Procedure

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.

Workup

temperatureThe reaction mixture was then cooled
customevaporated under reduced pressure to dryness
customThe residue was recrystallized from methanol

Sources & evidence

ORD record: ord-bc0143b715a6491eabcd30a5006aa220
Source dataset: uspto-grants-2013_04
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08410130B2

Reaction notes

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