Selective Isomerization of Terminal Alkenes to (Z)-2-Alkenes Catalyzed by an Air-Stable Molybdenum(0) Complex

Abstract

Positional and stereochemical selectivity in the isomerization of terminal alkenes to internal alkenes is observed using the cis-Mo(CO) 4 (PPh 3 ) 2 precatalyst. A p-toluenesulfonic acid (TsOH) cocatalyst is essential for catalyst activity. Various functionalized terminal alkenes have been converted to the corresponding 2-alkenes, generally favoring the Z isomer with selectivity as high as 8:1 Z:E at high conversion. Interrogation of the catalyst initiation mechanism by 31 P NMR reveals that cis-Mo(CO) 4 (PPh 3 ) 2 reacts with TsOH at elevated temperatures to yield a phosphine-ligated Mo hydride (MoH) species. Catalysis may proceed via 2,1-insertion of a terminal alkene into a MoH group and stereoselective β-hydride elimination to yield the (Z)-2alkene.

Base-Metal-Catalyzed Olefin Isomerization Reactions

“…Most olefin isomerization reactions are catalyzed by noble metals, such as ruthenium, 2 rhodium, 2j,3 palladium, 4 iridium, 5 platinum, 6 and molybdenum. 7 However, owing to the low abundance, high cost, and toxicity of precious metals, there is a growing tendency to substitute such catalysts with base-metal catalysts. Furthermore, owing to the unique structural and electronic properties of non-precious metals, olefin isomerization catalyzed by base metals might offer opportunities to discover new reactivities and selectivities differentiated from established precious-metalcatalyzed reactions.…”

Synthesis of nickel/gallium nanoalloys using a dual-source approach in 1-alkyl-3-methylimidazole ionic liquids

“…Utilizing clusters like [Cp*Ru(COD)Cl] in catalytic semihydrogenation reactions, the formation of only ( E )- [61–63] or ( Z )- [64–65] derivates are equally known [66]. When metal nanoparticles like the Lindlar catalyst PdPb@CaCO 3 are used, the formation of ( Z ) - alkenes [67–71] is favored.…”

Positional and Geometrical Isomerisation of Alkenes: The Pinnacle of Atom Economy

“…[27] Delineating the causes of undesirable side reactions in hydroformylation, leading to mixtures of linear/branched products,identified the role of cobalt hydride species in enabling positional isomerisation. [30] These conditions have since been translated to aplenum of metals including cobalt, [31] rhodium, [32] iridium, [33] molybdenum, [34] ruthenium, [35] platinum, [36] nickel, [37] iron, [38] and palladium. [39] Efficiency is typically contingent on alonglived metal hydride species or in situ generated hydride,a nd may proceed by two distinct mechanisms (Scheme 6).…”