Department of Chemistry, University of Basel , St. Johanns-Ring 19, CH-4056 Basel, Switzerland.
Institute of Technical Biochemistry, University of Stuttgart , Allmandring 31, D-70569 Stuttgart, Germany.
J Am Chem Soc. 2017 Aug 23;139(33):11482-11492. doi: 10.1021/jacs.7b04480. Epub 2017 Jun 23.
The tail-to-head terpene cyclization is arguably one of the most complex reactions found in nature. The hydrogen-bond-based resorcinarene capsule represents the first man-made enzyme-like catalyst that is capable of catalyzing this reaction. Based on noncovalent interactions between the capsule and the substrate, the product selectivity can be tuned by using different leaving groups. A detailed mechanistic investigation was performed to elucidate the reaction mechanism. For the cyclization of geranyl acetate, it was found that the cleavage of the leaving group is the rate-determining step. Furthermore, the studies revealed that trace amounts of acid are required as cocatalyst. A series of control experiments demonstrate that a synergistic interplay between the supramolecular capsule and the acid traces is required for catalytic activity.
头对头萜类环化反应可以说是自然界中最复杂的反应之一。基于氢键的间苯二酚杯芳烃胶囊代表了第一个能够催化这种反应的人工酶样催化剂。基于胶囊和底物之间的非共价相互作用，可以通过使用不同的离去基团来调节产物的选择性。进行了详细的机理研究以阐明反应机理。对于乙酸香叶酯的环化反应，发现离去基团的裂解是速率决定步骤。此外，研究还表明，需要痕量的酸作为共催化剂。一系列对照实验表明，超分子胶囊和酸痕之间的协同相互作用对于催化活性是必需的。
