102191-92-4

343338-28-3

918413-70-4

(2-tert-butyldimethylsilylmethoxy)acetaldehyde (54.64 mL, 258.2 mmol) was dissolved in dichloromethane (DCM, 500 mL), (S)-2-methylpropane-2-sulfinamide (34.42 g, 284.0 mmol) was added followed by copper sulfate (103.0 g, 645.4 mmol). The reaction mixture was stirred at ambient temperature for 48 hours. After completion of the reaction, the mixture was filtered through diatomaceous earth and washed with DCM. The filtrate was concentrated and purified by silica gel column chromatography (eluent: 10-30% hexane solution of ethyl acetate) to afford (S,E)-N-(2-((tert-butyldimethylsilylmethoxy)ethylidene)-2-methylpropane-2-sulfenamide (67.3 g, 94% yield).