Br[CH:2]1[CH2:6][CH2:5][O:4][C:3]1=[O:7].C([O-])([O-])=O.[K+].[K+].C([O:18][C:19](=[O:22])[CH2:20][SH:21])(C)(C)C>CC#N>[O:7]=[C:3]1[CH:2]([S:21][CH2:20][C:19]([OH:22])=[O:18])[CH2:6][CH2:5][O:4]1To a solution of 3-bromo-dihydro-furan-2-one (16 g, 97.6 mmol) in 300 mL of CH3CN was added K2CO3 (20 g, 146 mmol), followed by mercapto-acetic acid tert-butyl ester (14.5 g, 98 mmol). The reaction mixture was refluxed for 2 hrs and cooled. The mixture was filtered and the filtrate was concentrated. The residue was redissolved in 300 mL of EtOAc and the resulting solution was washed with 1N HCl (100 mL*2). The organic layer was dried over MaSO4, filtered andconcentrated to afford the ter-butyl ester title compound (23 g). 16 g of the ester was dissolved in 250 ml of HCl-MeOH (4M) and stirred at 25° C. for 4 hrs. The reaction mixture was concentrated below 45° C. in vacuum. The residue was purified by column chromatography (EtOAc) to afford 7 g of the title compound.
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