SmI(2)/amine/water mediates instantaneous cleavage of tosyl amides and tosyl esters. Highly hindered, sensitive and functionalized substrates were successfully deprotected in near quantitative yield.
Transition-metal-catalyzed alkenylation of enolates provides a direct method to synthesize broadly useful β,γ-unsaturated carbonyl compounds from the corresponding carbonyl compound and alkenyl halides. Despite being reported in the early seventies, this reaction class saw little development for many years. In the past decade, however, efforts to develop this reaction further have increased considerably, and many research groups have reported efficient coupling protocols, including enantioselective versions. These reactions most commonly employ palladium catalysts, but there are also some important reports using nickel. There are many examples of this powerful transformation being used in the synthesis of complex natural products.
Sm(HMDS)(2) in n-hexane mediates fast cleavage of primary, secondary and tertiary alkyl fluorides in good to excellent yields. In n-hexane Sm(HMDS)(2) exhibits uniquely enhanced reductive ability towards the C-F bond compared to when using THF as solvent.
A procedure for Ni-catalyzed cross-coupling of ketone enolates with alkenyl halides has been developed. Intermolecular coupling of aromatic and aliphatic ketone lithium enolates with a variety of alkenyl halides is achieved in the presence of Ni(cod)2 catalyst (5 mol %), an N-heterocyclic carbene (NHC) ligand, and LiI (10 mol %) at 6-22 °C for 0.5-12 h with yields of up to 90%. During the initial development of this reaction, a misleading result with respect to the actual active catalyst was obtained using commercially available Q-Phos ligand, which was found to contain a trace of Pd metal contaminant sufficient to catalyze the reaction. However, under the final conditions optimized for Ni(cod)2 in the presence of an NHC ligand, Pd was incompetent as a catalyst.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.