Under a nitrogen atmosphere, a 0.5 M solution of benzylzinc bromide in THF (3.11 mL, 1.556 mmol) was added to a mixture of ethyl 1-methyl-8-(methylthio)-4,5-dihydro-1H-pyrazolo[4,3-h]quinazoline-3-carboxylate (237 mg, 0.778 mmol) and Pd(PPh3)4 (9 mg, 0.0078 mmol, 1%). After 20 hours of heating at 60° C. under nitrogen, the mixture was cooled to room temperature, shaken with aqueous sodium bicarbonate and ethyl acetate and then filtered. The organic phase was then separated and the aqueous phase was extracted twice with ethyl acetate. The combined organic phase was dried over Na2SO4, evaporated and the crude was purified on silica gel (eluant dichloromethane/methanol 97/3). 20 mg of the title compound were isolated.
