Nickel-catalyzed reductive coupling of unactivated alkyl bromides and aliphatic aldehydes

Abstract

A mild, convenient coupling of aliphatic aldehydes and unactivated alkyl bromides has been developed. The catalytic system features the use of a common Ni(II) precatalyst and a readily available bioxazoline...

Catalytic Aldehyde and Alcohol Arylation Reactions Facilitated by a 1,5-Diaza-3,7-diphosphacyclooctane Ligand

“…While substantial efforts have been made to generalize the NHK reaction and render chromium catalytic, most practical applications use a substantial excess . Organometallic nucleophiles are still broadly used in carbonyl addition, , though progress toward the development of catalytic carbonyl reductive couplings by using nonmetallic reductants (H 2 , 2-PrOH) and related hydrogen autotransfer reactions has been made …”

Reductive 1,2-Arylation of Isatins

“…4 More recently, a number of catalytic reductive couplings have been reported that react organo(pseudo)halides with carbonyls using stoichiometric reductants such as Mn and Zn. 5 Use of mild organic reducing agents is less common in these intermolecular couplings, but recent successes with sodium formate 6 and 1-phenylethanol 7 indicates that stoichiometric metal additives are not inherently necessary. Notably, these reactions all feature aldehydes as the electrophilic carbonyl component.…”

Nickel-Catalyzed Diastereoselective Cross-Electrophile Ring Opening of 7-Oxabenzonorbornadienes with Aromatic Aldehydes

“…Furthermore, Montgomery et al successfully implemented the catalytic system of nickel and silyl chloride in the cross-electrophile coupling of aliphatic aldehydes with unactivated alkyl halides, tosylates, and redox-active esters, as well as epoxides. 5,6 Ring opening of strained oxabicyclic alkenes has emerged as a powerful tool for the straightforward and stereoselective synthesis of 1,2-dihydronaphthalenes. The main advances in this field are constrained to the reactions using a nucleophile as the coupling partner, e.g., diverse organometallics, amines, alcohols, phenols, thiophenols, carboxylic acids, terminal alkynes, halides, and hydride.…”

“…Recently, our group , and Montgomery independently developed allylic defluorinative ketyl olefin coupling under the catalysis of chromium, iron, or nickel to access gem -difluorohomoallylic alcohols, wherein α-silyloxyalkyl metal species are involved as key intermediates. Furthermore, Montgomery et al successfully implemented the catalytic system of nickel and silyl chloride in the cross-electrophile coupling of aliphatic aldehydes with unactivated alkyl halides, tosylates, and redox-active esters, as well as epoxides. , …”

“…Initially, Ni(0) is generated under reductive conditions and forms α-silyloxyalkyl nickel­(II) species A with benzaldehyde and TESCl . Subsequently, reduction of intermediate A by Zn results in the formation of α-silyloxyalkyl nickel­(I) species B , − to the Ni–C bond of which oxabicyclic alkene 1a performs an intermolecular migratory insertion. In favorable six-membered ring transition state C , the Ph moiety takes the axial position to avoid steric repulsion with the bicyclic alkene scaffold, giving rise to the generation of major diastereomer D .…”