To a sealed tube was added (S)-3-(3-bromopyrazolo[1,5-a]pyrimidin-5-yl)-4-(4-fluorophenyl)oxazolidin-2-one (Preparation A; 0.200 g, 0.530 mmol), 4-(tert-butoxycarbonyl)phenyl boronic acid (0.177 g, 0.795 mmol) and 2.0 M Na2CO3 (0.795 mL, 1.59 mmol) in dioxane (1 mL). The mixture was degassed by bubbling N2 through the solution. Pd2 dba3 (0.0486 g, 0.053 mmol), and dicyclohexyl(2′,4′,6′-triisopropylbiphenyl-2-yl)phosphine (0.0253 g, 0.053 mmol) were added and the vessel was sealed under a N2 atmosphere. The mixture was heated at 90° C. for 18 hours. The reaction mixture was cooled to ambient temperature, filtered through glass fiber filter paper, concentrated and purified on silica gel (10-100% ether in DCM) giving (S)-tert-butyl 4-(5-(4-(4-fluorophenyl)-2-oxooxazolidin-3-yl)pyrazolo[1,5-a]pyrimidin-3-yl)benzoate (0.148 g, 59% yield).
