Trifluoroacetic acid → 2-(4-Nitrophenyl)ethyl pyrrolo[4,5-e]indoline-7-carboxylate

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Reaction Steps

Two grams (4.43 mmol) of 14 are weighed into a round bottomed flask. Then, in a fume hood, 25 mL (325 mmol) of trifluroacetic acid is added, and the flask is capped and stirred. The solid dissolves in about a minute. The mixture is stirred for 1 hour, at which time deprotection will be done (HPLC can be used as a check). The acid is evaporated on a rotary evaporator (use a trap) and the product is dissolved in 100 mL of methylene chloride. This is extracted twice with 100 mL of half to 2/3 saturated sodium bicarbonate solution. The aqueous layers are back-extracted once with ˜50 mL of methylene chloride and this is combined with the rest. The organic layer is dried over sodium sulfate twice and evaporated to give a brown solid. If desired, this material can be recrystallized by diluting a very concentrated solution in methylene chloride with methanol and cooling. Yields approaching 100% are usually obtained. mp 192-194° C. 1H NMR (DMSO-d6) δ 11.51 (s, 1H), 8.18 (d, J=8.5 Hz, 2H), 7.63 (d, J=8.5 Hz, 2H), 7.11 (d, J=8.5 1H), 6.80 (s, 1H), 6.70 (d, J=8.5 Hz), 5.03 (br s, 1H), 4.54 (t, J=6.4 Hz, 2H), 3.46 (t, J=8.6 Hz, 2H), 3.19 (m, 2H), 3.04 (t, J=8.6 Hz, 2H). Combustion Analysis: Calculated for C19H17N3O4: C, 64.94%; H, 4.88%; N, 11.96%. Found: C, 65.50%; H, 4.70%; N, 11.64%

Provenance & Evidence