A supramolecular microenvironment strategy for transition metal catalysis

1. David M. Kaphan1,2,*, 
2. Mark D. Levin2,*, 
3. Robert G. Bergman1,2,†, 
4. Kenneth N. Raymond1,2,†, 
5. F. Dean Toste1,2,†

Science 4 December 2015: 
Vol. 350 no. 6265 pp. 1235-1238 
DOI: 10.1126/science.aad3087

http://www.sciencemag.org/content/350/6265/1235.full

A self-assembled supramolecular complex is reported to catalyze alkyl-alkyl reductive elimination from high-valent transition metal complexes [such as gold(III) and platinum(IV)], the central bond-forming elementary step in many catalytic processes. The catalytic microenvironment of the　supramolecular assembly acts as a functional enzyme mimic, applying the concepts of enzymatic catalysis to a reactivity manifold not represented in biology. Kinetic experiments delineate a Michaelis-Menten–type mechanism, with measured rate accelerations (kcat/kuncat) up to 1.9 × 107 (here kcat and kuncat are the Michaelis-Menten enzymatic rate constant and observed uncatalyzed rate constant, respectively). This modality has further been incorporated into a dual catalytic cross-coupling reaction, which requires both the supramolecular microenvironment catalyst and the transition metal catalyst operating in concert to achieve efficient turnover.