Synthesis of 4-(5-[18F]fluoromethyl-3-phenylisoxazol-4-yl)-benzenesulfonamide, a new [18F]fluorinated analogue of valdecoxib, as a potential radiotracer for imaging cyclooxygenase-2 with positron emission tomography

Abstract Fluoroalkyl and fluoroaryl analogues of valdecoxib were found to possess potent inhibitory activities against cyclooxygenase-2 comparable to that of the parent valdecoxib. Among them, the fluoromethyl analogue was chosen for 18 F-labeling. Thus, 4-(5-[ 18 F]fluoromethyl-3-phenylisoxazol-4-yl)benzenesulfonamide (∼2000 Ci/mmol at end of synthesis) was synthesized by [ 18 F]fluoride-ion displacement of the corresponding tosylate in ∼40% decay-corrected radiochemical yield within ∼120 min from end of bombardment.