Design and synthesis of spiro-linked azacycloalkane–dihydropyrano[4,3-d]pyrimidine compounds

New dihydropyrano[4,3-d]pyrimidines bearing 7-positioned spiro-linked azacycloalkane moieties were obtained by the Prins spirocyclization of commercially available N-protected azacycloalkanones followed by the regiospecific condensation with dimethylformamide dimethyl acetal and amidines. The new scaffold thus accessed appears to be a valuable building block for drug development.