QM and QM/MM studies of selectivity in organic and bioorganic chemistry

Electronic structure methods are used to explore the origin of selectivity in a number of organic, organometallic and bioorganic processes. Diastereoselectivity in reactions of sulfur and phosphorus ylides is shown to arise during a variety of different elementary steps, and is due to steric and electronic effects. Unusual rearranged products from Heck reaction of o ‐bromo biphenyl derivatives are shown to result from an unusual electrophilic addition step. Predicting selectivity in oxidation of aromatic substrates by cytochrome P450 isoforms is a challenging problem, which can be tackled using hybrid QM/MM methods. Differences in the electronic structure of the Compound I active intermediates of different cytochrome P450 isoforms do not appear to be large enough to explain the different selectivity of these different isoforms. Copyright © 2006 John Wiley & Sons, Ltd.