Development of multidrug resistance (MDR) during chemotherapy is a fundamental obstacle associated with cancer care. Prior studies have identified (2-(4-methoxyphenyl)-4- quinolinyl)(2-piperidinyl) methanol (5)(NSC23925) to be a small molecule agent that reverses MDR in cancer cells. We synthesized all four isomers of 5 and analyzed them by liquid chromatography–mass spectrometry (LCMS). Structure–activity relationships for ...