The synthetic procedure of this compound is analogous to EXAMPLE 6 wherein tert-butyl 2-(4-(bromomethyl)phenyl)pyrrolidine-1-carboxylate is used in step 2 instead of 2-(4-(chloromethyl)phenyl)pyridine. The obtained tert-butyl 2-(4-((5-chloro-1-isobutyl-3-methyl-2,4-dioxo-1,2,3,4-tetrahydropyrrolo[3,4-d]pyrimidin-6-yl)methyl)phenyl)pyrrolidine-1-carboxylate is deprotected with TFA in CH2Cl2 at room temperature to give 5-chloro-1-isobutyl-3-methyl-6-(4-(pyrrolidin-2-yl)benzyl)-1H-pyrrolo[3,4-d]pyrimidine-2,4(3H,6H)-dione, which is N-methylated with 37% formaldehyde aqueous solution and sodium borohydride in methanol at room temperature to give 5-chloro-1-isobutyl-3-methyl-6-(4-(1-methylpyrrolidin-2-yl)benzyl)-1H-pyrrolo[3,4-d]pyrimidine-2,4(3H,6H)-dione in a good overall yield. The obtained intermediate reacts with aniline using the procedure described in step 3 of EXAMPLE 6 to give pure product after HPLC purification. MS (ESI) m/z 486.3 [M+H]+.
