1283676-21-0Relevant articles and documents
On the mechanism and selectivity of the combined C-H activation/Cope rearrangement
Hansen, Jorn H.,Gregg, Timothy M.,Ovalles, Stephanie R.,Lian, Yajing,Autschbach, Jochen,Davies, Huw M. L.
, p. 5076 - 5085 (2011)
The combined C-H activation/Cope rearrangement (CHCR) is an effective C-H functionalization process that has been used for the asymmetric synthesis of natural products and pharmaceutical building blocks. Up until now, a detailed understanding of this process was lacking. Herein, we describe a combination of theoretical and experimental studies that have resulted in a coherent description of the likely mechanism of the reaction. Density functional studies on the reactions of rhodium vinylcarbenoids at allylic C-H sites demonstrate that the CHCR proceeds through a concerted, but highly asynchronous, hydride-transfer/C-C bond-forming event. Even though most of the previously known examples of this process are highly diastereoselective, the calculations demonstrate that other transition-states and stereochemical outcomes might be possible by appropriate modifications of the reagents, and this was confirmed experimentally. The calculations also indicate that there is a potential energy surface bifurcation between CHCR and the competing direct C-H insertion.
