Sulfuric acid magnesium salt (1:1) → 6-[(3-Ethoxycarbonyl-propylamino)-methyl]-indole-1-carboxylic acid tert-butyl ester

Participants

Reaction Conditions

Reaction Steps

To a solution of 4-amino-butyric acid ethyl ester hydrochloride (1 eq.) in either MeOH or EtOH were added TEA (2.5 eq.), 6-formyl-indole-1-carboxylic acid tert-butyl ester (0.95 eq.) and MgSO4 (1.5 eq.). The reaction was stirred at 20° C. for 15 h, then cooled to −15° C. NaBH4 (2 to 6 eq.) was added portionwise. The reaction was stirred for 1 h at −15° C., then 1 h at 0° C. The reaction was quenched with the addition of cold water at 0° C. The crude was extracted three times with DCM. The organic layers were combined, dried over MgSO4, filtered and concentrated under reduced pressure at 20° C. The crude was purified by chromatography on silica gel (elution with DCM/MeOH: 1/0 to 99/1) to afford 6-[(3-ethoxycarbonyl-propylamino)-methyl]-indole-1-carboxylic acid tert-butyl ester.

Provenance & Evidence