Ammonium Hydroxide → 6-{2-Amino-5,6,7,8-tetrahydropyrido[4,3-d]pyrimidin-6-yl}-N-[4-(isopropyl)phenyl]pyridine-2-carboxamide

A suspension of 6-(2-Methanesulfinyl-7,8-dihydro-5H-pyrido[4,3-d]pyrimidin-6-yl)-pyridine-2-carboxylic acid (4-isopropyl-phenyl)-amide (405 mg, 0.930 mmol) in 1,4-dioxane (10 ml) was treated with NH4OH (3 ml, 28-30%) and the reaction mixture was heated in a sealed tube at 100° C. with stirring for 15 hours. Upon cooling to room temperature, the reaction mixture was concentrated and the residue was taken up in water. The aqueous mixture was extracted with ethyl acetate and the organic extract was dried (MgSO4), filtered, and concentrated. Trituration with MeOH gave the title compound as a yellow, amorphous solid (200 mg, 55%).