1H-Indole-5-Carboxylic Acid → 1h-Indole-5-carboxamide,n-(cyclopentylmethyl)-

Participants

Reaction Steps

A solution of cyclopentylmethylamine (2.66 g), 5-carboxyindole (4.76 g), 4-(dimethylamino)pyridine (3.60 g) and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (5.67 g) in dichloromethane (60 ml) was stirred for 12 hours under an atmosphere of nitrogen. The amber solution was diluted with dichloromethane (150 ml), washed successively with 10% (w/v) aqueous sodium carbonate, 10% (v/v) hydrochloric acid, water, and brine, dried (MgSO4), and evaporated. The residual amber oil was purified by flash chromatography on silica gel (700 ml), eluting with 1:3 v/v ethyl acetate:chloroform, to yield 5-(N-cyclopentylmethylcarbamoyl)indole (A) (5.17 g, 80%) as a white crystalline solid; mp 110°-112° C.; NMR (80 MHz, CDCl3): 1.0-2.4(broad m, 9H, cyclopentyl), 3.4(dd, 2H, CH2N), 6 2(broad, 1H, NH), 6.6(m, 1H, H3 -indole), 7.3(t, 1H, H2 -indole), 7.4(d, 1H, H7 -indole), 8.5(broad, 1H, CONH).

Provenance & Evidence