Scheme 2. (A) Synthesis of 4-QM Precursor and Its Activation in the Presence of KF and (B) Activation of 2-QM Precursor in the Presence of KF.
(A) (a) TBS-Cl, imidazole, in DMF, under nitrogen, at room temperature overnight; (b) NBS, AIBN, in CCl4, 85°C, 35 min; (c) KF, in phosphate buffer (pH 7.4) and ACN, room temperature, 30 min. (B) (a) KF, in phosphate buffer (pH 8.4) and water, 37°C, 30 min.