Palladium(II)-Catalyzed Allylic C-H Oxidation of Hindered Substrates Featuring Tunable Selectivity Over Extent of Oxidation
The use of Oxone and a palladium(II) catalyst enables the efficient allylic C-H oxidation of sterically hindered α-quaternary lactams which are unreactive under known conditions for similar transformations. This simple, safe, and effective system for C-H activation allows for unusual tunable selectivity between a two-electron oxidation to the allylic acetates and a four-electron oxidation to the corresponding enals, with the dominant product depending on the presence or absence of water. The versatile synthetic utility of both the allylic acetate and enal products accessible through this methodology is also demonstrated.
Additional Information© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. Received: May 5, 2015; Revised: June 23, 2015; Article first published online: 31 Jul 2015. This work was supported by the NSF under the CCI Center for Selective C-H Functionalization, CHE-1205646. Additional support was provided by Caltech and Amgen. Dr. Scott C. Virgil is thanked for helpful discussions. Dr. David VanderVelde (NMR), Dr. Michael K. Takase (X-ray crystallography), and Dr. Mona Shahgholi (HRMS) are acknowledged for assistance with structural determination and characterization. Guillermo A. Guerrero-Vásquez, Lukas J. Hilpert, and Dr. Wen-Bo Liu are acknowledged for experimental assistance.
Supplemental Material - anie_201504007_sm_miscellaneous_information.pdf