Abstract
Polysubstituted pyridines 4 bearing methoxyphenyl groups at different positions of the ring have been prepared by the alkylation of 6-thioxo-1,6-dihydropyridines 1 or by the oxidation of 1,4-dihydropyridine 6 with manganese triacetate. The multidrug resistance–modulating (P-glycoprotein inhibition) activity of pyridine derivatives 4 comparable with that of verapamil has been revealed.