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.