Highly efficient catalysis of the Kemp elimination in the cavity of a cubic coordination cage

作者：Cullen, William; Misuraca, M. Cristina; Hunter, Christopher A.^*; Williams, Nicholas H.^*; Ward, Michael D.^*

来源：Nature Chemistry, 2016, 8(3): 231-236.

DOI：10.1038/NCHEM.2452

• PHYSICAL ORGANIC-CHEMISTRY
• DIELS-ALDER REACTION
• SUPRAMOLECULAR CATALYSIS
• MOLECULAR RECOGNITION
• BENZISOXAZOLES
• DECOMPOSITION
• HYDROLYSIS
• MECHANISM
• GUESTS
• DEEP

The hollow cavities of coordination cages can provide an environment for enzyme-like catalytic reactions of small-molecule guests. Here, we report a new example (catalysis of the Kemp elimination reaction of benzisoxazole with hydroxide to form 2-cyanophenolate) in the cavity of a water-soluble M8L12 coordination cage, with two features of particular interest. First, the rate enhancement is among the largest observed to date: at pD 8.5, the value of k(cat)/k(uncat) is 2 x 10(5), due to the accumulation of a high concentration of partially desolvated hydroxide ions around the bound guest arising from ionpairing with the 16+ cage. Second, the catalysis is based on two orthogonal interactions: (1) hydrophobic binding of benzisoxazole in the cavity and (2) polar binding of hydroxide ions to sites on the cage surface, both of which were established by competition experiments.

• 出版日期2016-3