Lithium hydroxide, monohydrate → Indole-2-carboxylic acid

To a solution of the above ether (770 mg, 2.1 mmol) in THF/MeOH (25 mL/10 mL) was added LiOH.H2O (218.1 mg, 2.50 eq) dissolved in 3 mL of water. The clear reaction solution was stirred at room temperature for 5 h, then concentrated in vacuo. The residual aqueous solution was diluted with water (15 mL), and extracted with ether. The organic layer was disgarded. The aqueous layer was acidified to pH 5 with 1.4 N HCl (˜2.5 mL). A large amount of white precipitates were extracted with 200 mL of EtOAc and washed with brine. The combined organics were dried over MgSO4, filtered and concentrated in vacuo to give the desired indole-2-carboxylic acid intermediate (644 mg, 90.5%) as a white foam.

1. concentrationconcentrated in vacuo
2. additionThe residual aqueous solution was diluted with water (15 mL)
3. extractionextracted with ether
4. customA large amount of white precipitates
5. extractionwere extracted with 200 mL of EtOAc
6. washwashed with brine
7. dry with materialThe combined organics were dried over MgSO4
8. filtrationfiltered
9. concentrationconcentrated in vacuo

ORD record

ord-223f23f07f944d399e0b2fe1221631f5

Source dataset

uspto-grants-2008_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07335657B2