Nitric Acid → cis-7-Nitro-2,3,4,4a,9,9a-hexahydro-1H-indeno[2,1-b]pyridin-6-ol

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Reaction Steps

A ca. 10° C.-cold mixture of nitric acid (65%, 0.36 mL) and sulfuric acid (96%, 0.55 mL) is added dropwise to a solution of trifluoro-methanesulfonic acid cis-1-(2,2,2-trifluoro-acetyl)-2,3,4,4a,9,9a-hexahydro-1H-indeno[2,1-b]pyridin-6-yl ester (2.00 g) in sulfuric acid (96%, 12 mL) chilled in an ice bath. The solution is stirred in the cooling bath for 1 h and poured then onto crushed ice. The precipitate formed is separated by filtration and taken up in methanol (10 mL). The resulting solution is treated with saturated aqueous K2CO3 solution (alternatively NaOH is used) until the trifluoromethylsulfonyl and trifluoroacetyl group are cleaved off (TLC or HPLC). Water is then added and the resulting mixture is extracted with ethyl acetate. The combined extract is concentrated to give the crude title compound that is used without further purification. Yield: 1.10 g (crude); LC (method 1): tR=1.44 min; Mass spectrum (ESI+): m/z=235 [M+H]+.

Provenance & Evidence