CCB Organic Seminar Series lecture presentation by Dr. James Stambuli, The Ohio State University.
Host: Dr. Daniel Seidel
Sponsored in Part by Organic Syntheses, Inc.
Talk Title: "C-H Activation Reactions Promoted by Iridium and Palladium"
Abstract: In recent years, the activation of C-H bonds has been transformed from an undesired step that deactivates a catalyst, to one that is synthetically useful. Many of these transformations involve the functionalization of arenes or allylic systems via their C-H bonds. We have developed several C-H activation reactions, but this talk will focus on the intermolecular allylic oxidation of vinylsilanes using low catalyst loadings of Pd(OAc)2 to produce the corresponding allylic acetates. Interestingly, trans-vinylsilanes are unreactive, whereas allylic oxidation reactions of cis-vinylsilanes proceed in good yields giving a single diastereo- and regioisomer of the branched allylic acetate trans-vinylsilane when benzoquinone (BQ) is employed. The use of PhI(OAc)2 as oxidant in place of BQ provides the branched, cis-vinylsilane as the major product. Intramolecular allylic etherifications of cis-vinylsilanes that give the corresponding vinyl tetrahydrofurans and -pyrans will also be presented. Our current efforts toward a mild, regioselective dehydrogenation of unactivated alkanes to alkenes using novel iridium complexes will also be discussed.
Check, C. T.; Henderson, W. H.; Wray, B. C.; Vanden Eynden, M. J.; Stambuli, J. P. Oxidant-Controlled Stereoselectivity in the Pd-Catalyzed Allylic Oxidation of cis-Vinylsilanes. J. Am. Chem. Soc., 2011, 133, 18503.
Whittemore, S. M.; Gallucci, J.; Stambuli, J. P. Synthesis and Reactivity of an Anionic Ir(III) Complex [Cp*Ir(OTf)3]Ag[tBu2P(heptanoyl)]. Organometallics, 2011, 30, 5273.