RAPID, STEPWISE SUBSTITUTION OF FLUORINES IN 5-TRIFLUOROMETHYL-2'-DEOXYURIDINE BY BISULFITE

On treatment with bisulfite at neutral pH, 5-trifluoromethyl-2'-deoxyu ridine (CF(3)dUR) underwent rapid substitution of the fluorine atoms b y bisulfite to give first the monosulfonate and then the disulfonate d erivatives. It was shown that the monosulfonate product has reactivity to bisulfite with a potency half that of CF(3)dUR. These findings dem onstrate the stepwise nature of the fluorine release from CF(3)dUR and constitute evidence that 5-exo-methylene type intermediates are invol ved in the nucleophile-mediated release of the fluorine from CF(3)dUR.