Efficient Access to 2,7-Diarylated Pyrido[3,2-d]pyrimidines Involving Regioselective­ Pallado-dehalogenation and Suzuki Cross-Coupling Reactions

An efficient and original synthesis of various 2,7-disubstituted pyrido[3,2- d ]pyrimidines is reported. The first synthesis of 2,7-dichloropyrido[3,2- d ]pyrimidine, by selective palladium-catalyzed dechlorination of 2,4,7-trichloropyrido[3,2- d ]pyrimidine at C-4, is described and its chemical reactivity is examined. Diarylated pyrido[3,2- d ]pyrimidines were synthesized starting from 2,7-dichloropyrido[3,2- d ]pyrimidine by regioselective Suzuki cross-­coupling reaction at C-2 and then at C-7.