Retardation of the Cleavages of Nitrophenyl 1-Adamantanecarboxylates by Cyclodextrins

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Abstract
Cleavages of p- and m-nitrophenyl 1-adamantanecarboxylates (1 and 2) were carried out in the presence of α-, β-, and γ-cyclodextrins at 16 °C. The complex formation of 1 with α-, β-, and γ-cyclodextrins decelerated its cleavage by 3.2, 28, and 13 fold, respectively, in the 99 : 1 (v/v) mixture of 0.1 mol dm−3 NaOH aqueous solution and acetonitrile. All α-, β-, and γ-cyclodextrins showed decelerations of the cleavages of 1 and 2 also in the 66 : 34 mixture of 0.1 mol dm−3 NaOH aqueous solution and acetonitrile, although the magnitudes of the rate effects were smaller. The decelerations of the cleavages of 1 and 2 by cyclodextrins were markedly in contrast with the accelerations of the cleavages of other phenyl esters by cyclodextrins previously reported, and were ascribed to the formation of the complexes, in which 1 and 2 were protected sterically and/or electrostatically by cyclodextrins.