Synthesis and biological evaluations of condensed pyridine and condensed pyrimidine-based HMG-CoA reductase inhibitors

A series of 3,5-dihydroxyheptenoic acid derivatives containing pyrazolopyridine, isoxazolopyridine, thienopyridine, and pyrazolopyrimidine as a key scaffold was synthesized from condensed pyridine and condensed pyrimidine carboxylic acid esters by homologation, aldol condensation with ethyl acetoacetate dianion, and stereoselective reduction of the 5-hydroxyketone. Several compounds in the series were found to have potent HMG-CoA reductase inhibitory activities in vitro and marked cholesterol biosynthesis inhibitory activities in vivo. It has been shown that these scaffolds can be used as a suitable replacement for the hexahydronaphthalene ring present in naturally occurring HMG-CoA reductase inhibitors.