Carbon Dioxide → 76369-00-1

Lit. Tetrahedron, 41:5633 (1985). To a stirred solution of 10.0 g (90.0 mmol) pyrrole-2-carboxylic acid in 180 ml dioxane was added dropwise at 0° C. 18 ml concentrated sulphuric acid 2-methylpropene was then condensed into the reaction flask over the course of 1 h, using a dry-ice condenser, and stirring continued for 16 h at 0° C. while the dry-ice condenser was periodically refilled so as to maintain a slow reflux of 2-methylpropene. The reaction mixture was then poured cautiously into an ice cooled mixture of 400 ml ether and 150 ml 2 M sodium hydroxide solution. The phases were separated and the aqueous phase extracted twice more with ether. The combined organic phases were washed successively with 2 M sodium hydroxide solution, water and finally with saturated brine, then dried over sodium sulphate and concentrated in vacuo to afford 9.07 g (60%) of the title compound as a colorless oil which still contained some dioxane. 1H NMR d (250 MHz, CDCl3) 9.60 (1H, br s), 6.90 (1H, m), 6.83 (1H, m), 6.22 (1H, m), 1.56 (9H, s).

1. customcondensed into the reaction flask over the course of 1 h
2. additionwas periodically refilled so as
3. temperatureto maintain
4. temperaturecooled
5. customThe phases were separated
6. extractionthe aqueous phase extracted twice more with ether
7. washThe combined organic phases were washed successively with 2 M sodium hydroxide solution, water and finally with saturated brine
8. dry with materialdried over sodium sulphate
9. concentrationconcentrated in vacuo

ORD record

ord-ffaf0afd77804d068cfffa46fd572a97

Source dataset

uspto-grants-2001_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06262089B1