A cooled (−78° C.) yellow solution of 2-iodo-1,3-dimethoxybenzene (8.553 g; 32.39 mmol) in anh. THF (175 ml), under nitrogen, was treated dropwise with a solution of 1.6 M n-BuLi in hexanes (20.25 ml; 32.40 mmol). The resulting slightly yellow solution was further stirred at −78° C. for 15 min. A yellow solution of ethyl 4-((tert-butylsulfinyl)imino)-2-methylbutanoate (6.410 g; 25.91 mmol) in anh. THF (15 ml) was then added dropwise to the cooled reaction mixture, and stirring at −78° C. was continued for 30 min. The resulting yellow reaction mixture was treated successively with aq. sat. NH4Cl (80 ml), Et2O (250 ml) and water (75 ml). The separated yellow organic layer was then washed with brine (75 ml), dried over anh. MgSO4, filtered, and concentrated to dryness under reduced pressure. Purification by FC (DCM/MeOH=25/1) afforded ethyl 4-(2,6-dimethoxyphenyl)-4-(1,1-dimethylethylsulfinamido)-2-methylbutanoate as an orange oil. LC-MS (conditions B): tR=0.88 min. and [M+H]+: 386.15 g/mol; tR=0.89 min. and [M+H]+: 386.14 g/mol (mixture of diastereoisomers).
