To a mixture of 7-(1-azidoethyl)-6-bromo-3-methyl-5H-[1,3]thiazolo[3,2-a]pyrimidin-5-one (1.24 g, 3.95 mmol) and (3,5-difluorophenyl)boronic acid (0.748 g, 4.74 mmol) in 1,4-dioxane (25 mL) was added a 1 N solution of sodium carbonate in water (5.92 mL, 5.92 mmol) and tetrakis(triphenylphosphine)palladium(0) (0.27 g, 0.24 mmol). The mixture was heated at 100° C. overnight. After cooling, the mixture was diluted with ethyl acetate, washed with water and brine, dried over MgSO4, and concentrated. The residue was purified on silica gel (0-40% EtOAc/Hex) to give the desired product (0.42 g, 31%). LCMS calculated for C15H12F2N5OS (M+H)+: m/z=348.1. Found: 348.0. The product was subjected to chiral HPLC separation (ChiralPak IA Column: 20×250 mm, 5 μm; Mobile Phase: 5% Ethanol 95% Hexanes; Flow Rate: 15 mL/min) to give two enantiomers. On analytic HPLC (ChiralPak IA Column: 4.6×250 mm, 5 μm; Mobile Phase: 5% Ethanol-95% Hexanes; Flow Rate: 1 mL/min), the first enantiomer has retention time of 7.78 min and the second peak has retention time of 8.61 minutes.
