Ruthenium-Catalyzed γ-Selective Intermolecular Amidation of Nonactivated Distal Methylene C-H Bonds of Terminal Alkenes via Olefin Chain-Walking Isomerization

Here we report the development of the [(p-cymene)Ru(II)]-catalyzed γ-selective intermolecular amidation of nonactivated distal methylene C-H bonds of terminal alkenes using sulfonyl azides and dioxazolones as the nitrogen sources. Initiated by the π-allyl Ru(II) complexes formation, the ruthenium complexes undergo spontaneous chain-walking isomerization via proton-assisted 1,3-allyl migration along the hydrocarbon chain. For alkenes containing a distal aryl substituent, the chain-walking isomerization afforded the aryl-conjugated alkenes as the most dominant isomerized products. With sulfonyl azides as the nitrogen source and the [(p-cymene)Ru] catalyst, the aryl-conjugated alkenes were further converted to the corresponding allyl tosylamides with >20:1 γ-selectivity. Unlike those cases with sulfonyl azide as the nitrene source, the analogous amidation with dioxazolones afforded the corresponding allylcarboximides in ca. 5:1 γ-selectivity. The nature of the chain-walking alkene isomerization and the origin of the γ-selectivity have been delineated.