3-(5-chlorofuran-2-yl)-5-methyl-4-phenylisoxazole and valdecoxib

3,4-Diarylisoxazole analogues of valdecoxib [4-(5-methyl-3-phenylisoxazol-4-yl)-benzensulfonamide], a selective cyclooxygenase-2 (COX-2) inhibitor, were synthesized by 1,3-dipolar cycloaddition of arylnitrile oxides to the enolate ion of phenylacetone regioselectively prepared in situ with lithium diisopropylamide at 0 degrees C. The corresponding 3-aryl-5-methyl-4-phenylisoxazoles were easily generated by a dehydration/aromatization reaction under basic conditions of 3-aryl-5-hydroxy-5-methyl-4-phenyl-2-isoxazolines and further transformed into their benzenesulfonamide derivatives. The biochemical COX-1/COX-2 selectivity was evaluated in vitro by using the human whole blood assays of COX isozyme activity. Three compounds not bearing the sulfonamide group present in valdecoxib were selective COX-1 inhibitors.

Topics: Adult; Biochemistry; Blood; Blood Platelets; Cyclooxygenase 1; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors; Dinoprostone; Dose-Response Relationship, Drug; Drug Evaluation, Preclinical; Female; Humans; Inhibitory Concentration 50; Isoenzymes; Isoxazoles; Lipopolysaccharides; Membrane Proteins; Monocytes; Prostaglandin-Endoperoxide Synthases; Structure-Activity Relationship; Sulfonamides; Thromboxane B2