α-Cyclodextrin-Catalyzed Regioselective P-O(2') Cleavages of 2',3'-Cyclic Monophosphates of Ribonucleosides

Article abstract of DOI:10.1021/ja00190a045

Regioselective P-O(2') cleavages of 2',3'-cyclic monophosphates of cytidine (1a), uridine (1b), adenosine (1c), and guanosine (1d) to the corresponding 3'-monophosphates (IIIa-d) are achieved at pH 11.08, 20 deg C by α-cyclodextrin (α-CyD) as catalyst.The selectivities asymptotically increase with increasing concentration of α-CyD, attaining 98, 94, 76, and 67percent for the cleavages of Ia-d, respectively, at the concentration of 0.05 M α-CyD.In the absence of α-CyD, however, significant concurrent cleavages of the P-O(3') bonds take place and the selectivities for IIIa-d are only 47, 50, 54, and 52percent.The rate of the P-O(2') cleavage of Ia in the α-CyD-Ia complex is 14 times as large as that of free Ia, and the rate of the P-O(3') cleavage in the complex is virtually zero. β- and γ-CyDs show no regioselective catalyses. 1H NMR spectroscopy indicates that the α-CyD-Ia and -Ib complexes are formed by hydrogen bondings and I's are located on the secondary hydroxyl side of the cavity of α-CyD.The selective cleavages of ribonucleotide dimers CpC, CpU, CpA, and CpG to IIIa are also successfully carried out by α-CyD as catalyst.