Water → HCID 21272031, compound

Participants

Reaction Steps

A mixture consisting of 4-methyl-7-(2,2,2-trifluoroethoxy)tryptophol (9.8 g, 0.036 mol), methyl 3-methoxy-2-pentenoate (5.0 g, 0.035 mol), CH2Cl2 (400 mL) and BF3.Et2O (1 mL) was stirred at room temperature for 3 hours, washed with 5% NaHCO3, water, dried (MgSO4) and concentrated to afford 12 g of crude 1-ethyl-1,3,4,9-tetrahydro-5-methyl-8-(2,2,2-trifluoroethoxy)-pyrano[3,4-b]indole-1-acetic acid, methyl ester. Flash chromatography using 13% EtOAc-hexane gave 7.2 g of solid ester, mp 138°-140° C. The above ester was hydrolyzed in 400 mL MeOH containing 7.0 g KOH and 10 mL water by refluxing for 4 hours. The reaction solution was concentrated, diluted with water and extracted with ether (2×200 mL). The aqueous phase was acidified with 6N HCl and extracted with chloroform (2×200 mL). The combined chloroform extracts were washed with water, dried (MgSO4) and concentrated to afford 6.4 g of solid 1-ethyl-1,3,4,9-tetrahydro-5-methyl-8-(2,2,2-trifluoroethoxy)-pyrano[3,4-b]indole-1-acetic acid. Recrystallization from toluene-petroleum ether afforded 5.0 g (37%) of pure product, m.p. 149°-151° C.

Provenance & Evidence