[(1S,5S)-3-[(1R)-1-Phenylethyl]-4-thioxo-3-azabicyclo[3.3.0]oct-7-en-1-yl]carboxylic acid tert-butyl ester → [(1S,5S)-3-[(1R)-1-Phenylethyl]-3-azabicyclo[3.3.0]oct-7-en-1-yl]carboxylic acid tert-butyl ester

[(1S,5S)-3-[(1R)-1-Phenylethyl]-4-thioxo-3-azabicyclo[3.3.0]oct-7-en-1-yl]carboxylic acid tert-butyl ester (88.2 mg, 0.27 mmol) was dissolved in ethanol. Raney nickel was added, and the mixture was stirred for one hour. The catalyst was removed by filtration, and then the filtrate was concentrated under reduced pressure. The resulting residue was subjected to silica gel column chromatography (10% ethyl acetate/hexane) to give 55.4 mg of the title compound as a colorless oil.