Diisopropylethylamine → 2-[(Benzo[b]thiophene-5-carbonyl)-amino]-indane-2-carboxylic acid ethyl ester

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Reaction Steps

To a 40 mL vial containing a stirring bar, benzo[b]thiophene-5-carboxylic acid (434 g, 2.44 mmol) is charged with dry DCM (7 mL). Stirring is initiated. HBTU (922 mg, 2.43 mmol) and DIPEA (0.95 mL, 8 mmol) are added. The 2-aminoindane-2-carboxylic acid ethyl ester (500 mg, 2.44 mmol) is added. The reaction is allowed to stir for 64 h. Analysis by tlc of the reaction mixture (silica, 10% MeOH/DCM) indicates complete consumption of the starting amine. The contents of the reaction flask are diluted with EtOAc (50 mL) and transferred to a separatory funnel. This is washed consecutively with dilute aqueous NaHCO3 (25 mL) and brine (25 mL), dried over MgSO4, filtered and evaporated in vacuo to provide 1.4 g of an off white solid. This material is purified utilizing an ISCO Companion with a 40 g cartridge of silica. The gradient is 10% EtOAc in heptanes over 3 column volumes followed by a linear gradient to 50% over 8 column volumes and then 90% EtOAc for 2 column volumes with a ramp of 1 column volume. 25 mL fractions are collected. Fractions 4 through 16 are combined and evaporated in vacuo. Pumping to a constant weight gives amorphous white solid 0.79 g.

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