Acetic Anhydride → 5,6-Diacetoxyindole

Participants

Reaction Steps

A suspension of 17.2 g of trans-4,5-dibenzyloxy-β-pyrrolidino-2-nitrostyrene (prepared from 3,4-dihydroxytoluene by a modified procedure of U.S. Pat. No. 3,732,245) and 3.4 g of 10% Pd/C catalyst in 200 ml ethyl acetate was shaken at room temperature, under hydrogen atmosphere and at 50 psi, for 5 hours. To this reaction mixture was added a solution of ethyl acetate (100 ml) containing acetic anhydride (24 ml), triethylamine (20 ml) and dimethylaminopyridine (800 mg) which was previously saturated with hydrogen. The resultant mixture was stirred for 30 minutes at room temperature. The catalyst was removed over a layer of Celite and the filtrate was evaporated to give an oily residue to which crushed ice was added. The resulting white precipitate was collected by filtration to give 6.08 g (65%) of DAI: mp 130°-131° C.; HNMR (300 MHz, DMSO-d6)δ 2.24 (s,6H), 6.42 (s,1H), 7.22 (s,1H), 7.32 (s,1H), 7.39 (m, 1H) 11.22 (s,1H).

Provenance & Evidence