Acetaldehyde → [(S)-7-Cyano-4-((2R,3S)-3-hydroxy-1-ethyl-pyrrolidin-2-ylmethyl)-1,2,3,4-tetrahydro-cyclopenta[b]indol-2-yl]-carbamic acid isopropyl ester

Participants

Reaction Steps

A solution of [(S)-7-cyano-4-((2R,3S)-3-hydroxy-pyrrolidin-2-ylmethyl)-1,2,3,4-tetrahydro-cyclopenta[b]indol-2-yl]-carbamic acid isopropyl ester (300 mg, 784.4 μmol) in acetonitrile (20 mL) is treated with acetaldehyde (1.0 mL, 17.80 mmol) and sodium triacetoxyborohydride (520 mg, 2.35 mmol) and stirred at room temperature overnight. The suspension is treated with saturated sodium bicarbonate solution (40 mL) and stirred for 30 min. The resulting suspension is diluted with dichloromethane (100 mL) and washed with water (3×100 mL) and brine. The organic portion is dried over sodium sulfate, filtered, and concentrated to dryness. The resulting residue is purified by medium pressure liquid chromatography, eluting with methanol:chloroform (5:95). Fractions containing pure product are combined and concentrated to afford 0.1 g (31%) of the title compound. LC-ES/MS m/z 144.2 [M+H]+, TR=1.94 min.

Provenance & Evidence