To a solution of (3aR,6aR)-tetrahydrofuro[3,4-d]oxazol-2(3H)-one (500 mg, 3.87 mmol), 4-(4,6-dichloropyrimidin-2-yl)morpholine (1088 mg, 4.65 mmol) and Cs2CO3 (2.14 g, 6.58 mmol) in dioxane (20 mL) was added after degassing with argon 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (157 mg, 0.271 mmol) and Pd2(dba)3 (70.9 mg, 0.077 mmol) and the reaction mixture was heated for 6 h at 85° C. The reaction mixture was added to 10% aqueous NaHCO3 solution and extracted with EtOAc. Combined extracts were washed with brine, dried over MgSO4, filtered and concentrated. The crude product was triturated in MeOH overnight, filtered off and dried to afford the title compound as a colorless solid (1.12 g, 87%): tR=0.92 min (LC-MS 3); ESI-MS: 327, 329 [M+H]+ (LC-MS 3).
