Cooperation of cyclodextrin and alkali-metal halide for regioselective cleavage of ribonucleoside 2′,3′-cyclic phosphates

Article abstract of DOI:10.1021/ja00029a040

Regioselective catalysis of β- and γ-cyclodextrins (β- and γ-CyDs) for the P-O(3′) cleavage of adenosine 2′,3′-cyclic phosphate (A>p) to adenosine 2′-phosphate is significantly promoted, with respect to both selectivity and reaction rate, by cooperation with NaCl, KCl, RbCl, CsCl, KBr, and KF. A selectivity of 94% is achieved at pH 9.5 and 30 °C by the combination of β-CyD and KCl (3.0 M); the values with β-CyD alone and with KCl alone are 79% and 41%, respectively. By contrast, LiCl and KI reduce the regioselectivity. The logarithm of the 2′-phosphate/3′-phosphate ratio decreases linearly with an increase in the logarithm of the mean ionic activity coefficient of the medium. The α-CyD-induced regioselective P-O(2′) cleavage of A>p and U>p to the 3′-phosphates is also enhanced by KCl. The difference in chemical environment of the P-O(2′) and P-O(3′) bonds provided by CyDs on complex formation with the cyclic phosphates is amplified by the metal salts, resulting in the increase in regioselectivity.