Tetrahydro-4H-pyran-4-one → 4-(6-((2H-pyran-4(3H,5H,6H)-ylidene)methyl)-2-chloropyrido[3,2-d]pyrimidin-4-yl)morpholine

To a suspension of dimethyl (2-chloro-4-morpholinopyrido[3,2-d]pyrimidin-6-yl)methylphosphonate from Example 117 (0.45 g) in anhydrous THF (6 mL) at 0° C. was added 2.0 M of lithium diisopropylamide in tetrahydrofuran (1.5 eq). The resulting solution was allowed to warm to RT before adding a solution of dihydro-2H-pyran-4(3H)-one (1.5 eq) in anhydrous THF (3 mL). The reaction mixture was stirred at room temperature for 1 h, then partitioned between brine and Ethyl Acetate. The organic layer was isolated, dried (MgSO4), concentrated and recrystallized from methanol. The light yellow solid was filtered and collected to give 0.36 g of 4-(6-((2H-pyran-4(3H,5H,6H)-ylidene)methyl)-2-chloropyrido[3,2-d]pyrimidin-4-yl)morpholine as a light yellow solid.