1260088-71-8

1260088-72-9

Step 3 - Synthesis of 2,4-dichloro-7,7-dimethyl-5,7-dihydrofuro[3,4-d]pyrimidine (p): a mixture of 7,7-dimethyl-5,7-dihydrofuro[3,4-d]pyrimidine-2,4(1H,3H)-dione (o) (2.55 g, 14.0 mmol), phosphinic acid chloride (15 mL, 160 mmol) and 1,2-dichloroethane ( The mixture of 80 mL) was heated at 80 °C for 20 hours. Upon completion of the reaction, the mixture was concentrated to a solid and partitioned between dichloromethane (250 mL) and saturated NaHCO3 solution (500 mL). The organic and aqueous phases were separated and the aqueous phase was extracted with dichloromethane (3 x 50 mL). The organic phases were combined, dried over anhydrous Na2SO4, filtered and concentrated to afford 2.53 g (82% yield) of 2,4-dichloro-7,7-dimethyl-5,7-dihydrofurano[3,4-d]pyrimidine (p) as a colorless solid. Product characterization data: 1H NMR (400 MHz, CDCl3) δ 5.02 (s, 2H), 1.51 (s, 6H); LC-MS: m/z = 219(M+H)+.