A Method for the Selective Hydrogenation of Alkenyl Halides to Alkyl Halides

Abstract

A general method for the selective hydrogenation of alkenyl halides to alkyl halides is described. Fluoro, chloro, bromo, iodo, and gem-dihaloalkenes are viable substrates for the transformation. The selectivity of the hydrogenation is consistent with reduction by a hydrogen atom transfer pathway.

Cobalt bis(acetylacetonate)–tert-butyl hydroperoxide–triethylsilane: a general reagent combination for the Markovnikov-selective hydrofunctionalization of alkenes by hydrogen atom transfer

“…In 2014, we reported the reduction of alkenyl halides (e.g., 1 , Scheme 2) utilizing Co(acac) 2 , TBHP, and two reductants, triethylsilane and 1,4-dihydrobenzene (DHB) [2]. Mechanistic studies showed that Et 3 SiH participates in the formation of a cobalt hydride intermediate that delivers a hydrogen atom to the less-substituted position of the alkene.…”

The Golden Age of Transfer Hydrogenation

“…473 Interestingly, the use of conjugated substrates including trans-4-phenyl-3-buten-2-one and cinnamaldehyde revealed that both CC and CO were completely reduced, affording the corresponding alcohols in 98% and 95% yields, respectively. Furthermore, mechanistic studies indicated that cobalt−ligand cooperativity was not 473 Herzon's group 474 reported a new route for the selective hydrogenation of alkenyl halides to alkyl halides catalyzed by [Co(acac) 2 ] through a HT pathway using both triethylsilane and 1,4-cyclohexadiene as hydrogen donors. This procedure tolerated various alkenyl compounds with fluoro, chloro, bromo, and iodo substituents, and the desired alkyl halides were isolated in moderate to good yields (Scheme 44).…”

Mn-, Fe-, and Co-Catalyzed Radical Hydrofunctionalizations of Olefins

“…Post 2014, this MH HAT hypothesis was suddenly and widely adapted in research articles and literature reviews to characterize the field. 5,6,7,24,27,397 …”