1-tert-butyl-8-(methylsulfanyl)-1H-pyrazolo[4,3-h]quinazoline-3-carboxylic acid 40 mg (0.112 mmol) was reacted in dry DMF (2 ml) with O-(tetrahydro-2H-pyran-2-yl)hydroxylamine 25 mg (0.21 mmol), TBTU 70 mg (0.21 mmol) and DIPEA 0.110 ml (1.19 mmol) at room temperature for 3 hours. The reaction was worked up with water, saturated NaHCO3 and extracted with ethyl acetate. The organic phase, dried on Na2SO4, filtered and evaporated, was purified on silica with DCM/EtOAc 7/3 to give 23 mg (50%) of 1-tert-butyl-8-(methylsulfanyl)-N-(tetrahydro-2H-pyran-2-yloxy)-1H-pyrazolo[4,3-h]quinazoline-3-carboxamide. LC/MS (m/z): 416.1 [M+H]+, HPLC (254 nm) method 3 Rt 6.94 min.
