Dimethyl acetylenedicarboxylate → 1,4-Dimethyl-7-aza-bicyclo[2.2.1]hepta-2,5-diene-2,3,7-tricarboxylic acid 7-tert-butyl ester 2,3-dimethyl ester

HRID 1441868Notes

Reaction equation

HRID 1441868 reaction equation
[C:1]([O:5][C:6]([N:8]1[C:12]([CH3:13])=[CH:11][CH:10]=[C:9]1[CH3:14])=[O:7])([CH3:4])([CH3:3])[CH3:2].[C:15]([C:21]([O:23][CH3:24])=[O:22])#[C:16][C:17]([O:19][CH3:20])=[O:18]>>[CH3:20][O:19][C:17]([C:16]1[C:12]2([CH3:13])[N:8]([C:6]([O:5][C:1]([CH3:4])([CH3:3])[CH3:2])=[O:7])[C:9]([CH3:14])([C:15]=1[C:21]([O:23][CH3:24])=[O:22])[CH:10]=[CH:11]2)=[O:18]

Participants

3

Reactant 2

HCID 12980Dimethyl acetylenedicarboxylateHCID 15587518tert-Butyl 2,5-dimethyl-1H-pyrrole-1-carboxylate

Product 1

HCID 587460711,4-Dimethyl-7-aza-bicyclo[2.2.1]hepta-2,5-diene-2,3,7-tricarboxylic acid 7-tert-butyl ester 2,3-dimethyl esterYield 50%

Procedure

A mixture of crude 2,5-dimethyl-pyrrole-1-carboxylic acid tert-butyl ester (prepared according to a literature (Haiser, H.-P.; et al. J. Org. Chem. 1984 49(22) 4203-4209); 500 mg) and dimethyl acetylenedicarboxylate (0.5 mL, ca 4 eq) was stirred at 120° C. under argon for 2 h. Purification by silica gel flash chomatography on SiO2 eluting with EtOAc/heptane (gradient from 1:20 to 1:2 ratio) gave compound 780A (166 mg, 50% yield) as a colorless liquid. HPLC: 90% at 3.67 min (retention time) (YMC S5 ODS-A column 4.6×50 mm eluting with 10-90% aqueous methanol over 4 mincontaining 0.2% phosphoric acid, 4 mL/min, monitoring at 220 nm).

Workup

  1. customprepared
  2. customPurification by silica gel flash chomatography on SiO2 eluting with EtOAc/heptane (gradient from 1:20 to 1:2 ratio)

Sources & evidence

ORD record
ord-a9cd8530ffd6415d9b2e53627583b5a2
Source dataset
uspto-grants-2010_02
Patent number
US07655689B2

Reaction notes

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