Tert-butyl 4-{6-bromo-1-[(3-ethyl-1,2,4-oxadiazol-5-yl)methyl]-2,4-dioxo-1,4-dihydrothieno[3,2-d]pyrimidin-3(2H)-yl}piperidine-1-carboxylate (540 mg, compound B99), (3,4-difluorophenyl)boronic acid (158 mg), dichlorobis(tricyclohexylphosphine)palladium (37 mg) and aqueous cesium carbonate solution (489 mg, 2.0 M) in DME (10 ml) are reacted according to the procedure described in example B55 to afford the title compound after purification by flash column chromatography [silica gel, elution gradient: cyclohexane/EtOAc, 70/30 to 50/50 to 30/70 (v/v)] as a solid.
