A cooled (−78° C.) solution of 5-bromo-4,6-dimethoxypyrimidine (473 mg; 2.15 mmol) in anh. THF (5 ml), under nitrogen, was treated dropwise with a solution of 1.6 M n-BuLi in hexanes (1.50 ml; 2.40 mmol). The resulting solution was further stirred at −78° C. for 10 min. A solution of methyl 5-((tert-butylsulfinyl)imino)pentanoate (503 mg; 2.15 mmol) in anh. THF (2 ml) was then added to the cooled reaction mixture, and stirring at −78° C. was continued for 60 min. The resulting reaction mixture was treated successively with aq. sat. NH4Cl (15 ml), Et2O (30 ml) and water (15 ml). The separated organic layer was then washed with brine (15 ml), dried over anh. MgSO4, filtered, and concentrated to dryness under reduced pressure. Purification by FC (DCM/MeOH=25/1) afforded methyl 5-(4,6-dimethoxypyrimidin-5-yl)-5-(1,1-dimethylethylsulfinamido)pentanoate as a yellow solid. LC-MS (conditions A): tR=0.66 min.; [M+H]+: 374.06 g/mol.
