To a solution of (S,E)-tert-butyl 2-((tert-butylsulfinylimino)methyl)thiazole-5-carboxylate (15 g, 47 mmol) in DCM (500 mL) at −70° C. was slowly added methylmagnesium bromide (63 mL, 3 M in ether). The mixture was stirred at −70° C. for 3 h then quenched with sat. NH4Cl solution. The solution was then warmed to rt. After separation, the aqueous phase was extracted with DCM (3×200 mL). Combined organic phases were dried (Na2SO4), and concentrated. Flash column chromatography (DCM:MeOH, 100:0 to 100:1) afforded tert-butyl 2-((R)-1-((S)-1,1-dimethylethylsulfinamido)ethyl)thiazole-5-carboxylate (10 g, 64%). 1H NMR (CDCl3, 400 MHz) δ 8.14 (s, 1H), 4.76 (m, 1H), 4.15 (m, 1H), 1.60 (d, J=6.8 Hz, 3H), 1.50 (s, 9H), 1.20 (s, 9H).
