from first principles PP-I-1

PL-4Catalysis & Complexity: From Mechanism to FunctionFokin V.V.The Scripps Research Institute, La Jolla, California 92037, USAfokin@scripps.eduCatalysis is at the heart of chemistry and disciplines that directly depend on it, for harnessingthe complexity of catalytic processes offers unprecedented potential for making them usefulon both laboratory and industrial scales. Investigation of complex catalytic systems requiresmethods that examine these processes under true bench top conditions in real time andthroughout their course. This global profiling approach allows us to study critically importantevents, such as activation and deactivation of catalysts, unproductive off-cycle pathways, andprovides insights into the dynamics of the changing environment of a catalytic reaction. Wethen use the resulting data-dense reaction profiles for the development of most efficientreaction conditions.A key lesson that emerged from our work during the last decade is that one can achieve nearperfect selectivity without relying on the classical lock and key enzymatic catalysis paradigmbecause highly dynamic mixtures of complexes that exist in rapid equilibria with each othercan actually serve as exquisitely selective catalysts. A single, well-defined catalyst is notalways required and may, in fact, be counterproductive. If allowed, the system will select, andwill inescapably form, the right catalyst – and it does not need to dominate as far aspopulation goes – as long as there is enough of it to effect the fastest catalytic turnover.This approach will be exemplified using several case studies of the catalytic reactions ofalkynes. Alkynes are among the most energetic hydrocarbons, and transition metals enableselective and controlled manipulation of the triple bond, opening the door to the wealth ofreliable reactivity: transformations of alkynes into heterocycles and into a variety ofmolecules with new carbon–heteroatom bonds. The combination of catalytic alkynefunctionalization followed by manipulation of the resulting products allows one to proceedfrom a system with high energy content to a system of lower energy in a stepwise fashion,thereby enabling controlled introduction of new elements of diversity in every step. Variousarchitectures prepared using these methods are finding increased use in organic synthesis,nano- and biotechnology, and materials science.10