Evidence for a Concerted Mechanism in a Palladium Trimethylenemethane Cycloaddition
Journal of the American Chemical Society1999Vol. 121(40), pp. 9313–9317
Citations Over TimeTop 24% of 1999 papers
Abstract
Carbon kinetic isotope effects were determined at natural abundance for the palladium trimethylenemethane cycloaddition of ester−amide 5. Substantial intermolecular 13C KIEs were observed for both olefinic carbons of 5. In contrast, a Michael addition to 5 exhibits a significant 13C KIE only at the carbon β to the ester group. Intramolecular KIEs determined for the product-determining step(s) for reaction of the Pd−TMM intermediate would require a surprising isotope-dependent selection between diastereomeric ring closures. These results cannot be reconciled with a stepwise cycloaddition mechanism but are readily interpreted in terms of a concerted cycloaddition.
Related Papers
- → Palladium-Catalyzed [3 + 3] Cycloaddition of Trimethylenemethane with Azomethine Imines(2006)171 cited
- → Tandem Cycloaddition Reactions of Allenyl Diazo Compounds Forming Triquinanes via Trimethylenemethane Diyls(2011)39 cited
- → Cycloaddition of Chiral tert-Butanesulfinimines with Trimethylenemethane(2013)36 cited
- → Total Synthesis of Ceratopicanol through Tandem Cycloaddition Reaction of a Linear Substrate(2012)19 cited
- → Asymmetric [3+3] Cycloaddition of Trimethylenemethane with Nitrones(2007)