SUMMARY
The literature references concerning the biological activity of pyrido[3,2-d]pyrimidines and condensed polycyclic systems based on them have been systematized and analyzed. The main methods of the synthesis of polyheterocycles containing the pyrido[3,2-d]pyrimidine moiety have been summarized. The synthetic potential of the electrophilic intramolecular cyclization as a convenient tool for the directed design of azolo- and azinoannelated pyrido[3,2-d]pyrimidine structures has been found. Regiochemistry of ann?lation of the functional fragment of 2-allyl(cinnamyl)aminopyrido[3,2-d]pyrimidines has been studied under the action of three types of electrophilic reagents: iodine, polyphosphoric acid and arylsulphenylchlorides. The correlations have been found between the nature of substrate, electrophile, reaction conditions and the direction of intramolecular cyclization. It has been found that cyclization of 2-allyl(cinnamyl)aminopyrido[3,2-d]pyrimidines in the presence of polyphosphoric acid leads to linear forms of imidazopyridopyrimidinon, while in the conditions of iodocyclization and arylsulfenylation the tricyclic imidazoannelated pyridopyrimidines of the angular structure are mainly formed. Regioselectivity of annelation of the 2-cinnamyl moiety of aminopyrido[3,2-d]pyrimidine has been found. In particular, treatment of 2-cinnamylaminopyrido[3,2-d]pyrimidine with arylsulphenylchlorides or polyphosphoric acid results in formation of the linear tetrahydropyrido[3,2-d]pyrimidines, and iodocyclization leads to an angular isomer. The virtual screening of the compounds synthesized has shown that they may potentially exhibit a wide range of bioactivity.