4-[3-(2-Ethoxycarbonyl-2-oxo-ethyl)-4-nitro-phenoxy]-piperidine-1-carboxylic acid tert-butyl ester → 5-(1-tert-Butoxycarbonyl-piperidin-4-yloxy)-1H-indole-2-carboxylic acid ethyl ester

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Reaction Steps

A mixture of 4-[3-(2-ethoxycarbonyl-2-oxo-ethyl)-4-nitro-phenoxy]-piperidine-1-carboxylic acid tert-butyl ester (example 43, step 2, 42.25 g, 1.0 eq.), palladium on activated charcoal (10%, 2.111 g, 0.02 eq.) in ethanol (950 mL) was hydrogenated at 30° C. for 9 h. The mixture was filtered, washed with ethanol and evaporated to dryness. The product was recrystallized from ethyl acetate and heptane to yield 25.998 g (69%) as white crystals. MS (m/e): 388.2 (M, 45%).

Provenance & Evidence