Development of an In Situ Protocol for the Intramolecular Olefination of Oximes

We herein report the development of a protocol for the olefination of oximes, resulting in cyclic alkene products. Our approach relies on the in situ formation of Ru alkylidenes from [RuCl2(p-cymene)]2 and 3,3-diphenylcyclopropene as carbene precursors and gives rise to the desired functionalized alkenes in yields up to 58%. Compared to our previously reported strategy for oxime olefination, it foregoes the use of commercially available Ru alkylidenes, including Hoveyda-Grubbs 2. This is desirable concerning the overall costs of this transformation and also provides important mechanistic insights into the development of future catalytic variants of this reaction as the alkylidenes required for efficient olefination can be generated in situ.