Cl.Br[CH2:3][C:4]([O:6][CH2:7][CH3:8])=[O:5].[CH:9]1(/[C:12](=[N:14]/[S:15]([C:17]([CH3:20])([CH3:19])[CH3:18])=[O:16])/[CH3:13])[CH2:11][CH2:10]1>C1COCC1.[Zn].[Cu]Cl>[C:17]([S:15]([NH:14][C:12]([CH:9]1[CH2:11][CH2:10]1)([CH3:13])[CH2:3][C:4]([O:6][CH2:7][CH3:8])=[O:5])=[O:16])([CH3:18])([CH3:19])[CH3:20]
To a flask containing zinc (Note: the zinc powder was activated by stirring 10 gr in 20 mL of 2.0M aqueous solution HCl (caution: strong exotherm occurs)) (3.49 g, 53.4 mmol) and copper (I) chloride (529 mg, 5.34 mmol) under a stream of argon was added dry THF (10.0 ml), the suspension was stirred at reflux for 30 minutes then the heating bath was removed. Slow addition of a solution of ethyl 2-bromoacetate (1.78 g, 10.7 mmol, Eq: 2.0) in dry THF (5.00 ml) (caution: reaction exothermic), when addition completed the suspension was stirred for 30 min at rt then 30 min at 50° C. The reaction was then cooled down to 0° C. and a solution of (E)-N-(1-cyclopropylethylidene)-2-methylpropane-2-sulfinamide (1 g, 5.34 mmol) in dry THF (5.00 ml) was added to the reaction. The reaction was then stirred at 0° C. and let to warm up to room temperature overnight. The reaction mixture was filtered through a pad of Celite and the filter pad was washed twice with ethyl acetate. The filtrate was washed with a 0.25M aqueous solution of citric acid, a 1M aqueous solution of sodium bicarbonate. The organic phase was dried over sodium sulfate and concentrated in vacuo. The crude material was purified by flash chromatography on silica eluting with a gradient of heptane/ethyl acetate to yield the title compound (1.16 g, 79%) as a yellow oil; MS (ESI, m/z): 276.3 (M+H+).
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