Efficient access to novel mono- and disubstituted pyrido[3,2-d]pyrimidines

New mono- and disubstituted pyrido[3,2-d]pyrimidines were synthesized starting from the corresponding 2,4-dichloro derivative through S N Ar and palladium-catalyzed reactions. S N Ar and palladium-catalyzed hydro-deshalogenation occurred selectively at position C-4. Further Suzuki cross-coupling led to C-2 and C-2,4 mono- and disubstituted compounds.