Methanol → 6-[1-(4-chlorophenyl)-cyclopentylmethyl]-2-cyclopropylmethyl-9-hydroxy-3,4-dihydro-2H-pyrazino[1,2-c]pyrimidine-1,8-dione

Participants

Reaction Steps

To a solution of 9-benzyloxy-6-[1-(4-chlorophenyl)-cyclopentylmethyl]-2-cyclopropylmethyl-3,4-dihydro-2H-pyrazino[1,2-c]pyrimidine-1,8-dione (331) (200 mg, 0.38 mmol) in acetic acid (6.0 mL) was added H2SO4 (0.05 mL) at 0° C. and the reaction mixture was stirred at room temperature for 2 h (TLC; 5% methanol in dichloromethane/UV/SiO2, Rf=0.3). The reaction mixture was quenched with NaHCO3 solution, diluted with water and extracted with ethyl acetate (2×50 mL). The organic part was washed with water (40 mL) and brine (40 mL). The organic phase was thereafter dried and concentrated in vacuo to get a brownish gummy mass which was dissolved in dichloromethane (1 mL). 5 mL of hexane was added to the solution and the solid formed was allowed to settle down. The liquid phase was removed by decantation and the solid was triturated with diethyl ether and n-pentane to get pure 6-[1-(4-chlorophenyl)-cyclopentylmethyl]-2-cyclopropylmethyl-9-hydroxy-3,4-dihydro-2H-pyrazino[1,2-c]pyrimidine-1,8-dione (332) (86 mg, 52%) as a light brown solid.

Provenance & Evidence