Scope and Mechanism of Allylic C−H Amination of Terminal Alkenes by the Palladium/PhI(OPiv)₂ Catalyst System: Insights into the Effect of Naphthoquinone

Palladium-catalyzed oxidative amination of unactivated alkyl olefins has been developed to produce linear (E)-allylimides with high regioselectivity. This highly efficient transformation of alkenes has been achieved by enhancing the reoxidation of palladium with the strong oxidant PhI(OPiv)2. The present work also provides the first systematic analysis of the mechanism of the allylic C−H oxidative amination. It has been found that naphthoquinone (NQ) plays a vital role in promoting olefin coordination to the palladium catalyst: in the absence of NQ, the turnover-limiting step is olefin coordination to palladium catalyst; in the presence of NQ, the reaction involves a rapid equilibration to give a nitrogen-coordinated olefin-Pd(NQ) complex that undergoes turnover-limiting allylic C−H bond activation to generate a π-allyl-Pd intermediate. This work provides valuable insights for further studies on the functionalization of unactivated olefins

Palladium-Catalyzed Intramolecular Aminofluorination of Unactivated Alkenes

Palladium-Catalyzed Intramolecular Aminofluorination of Unactivated Alkene

Scope and Mechanism of Allylic C−H Amination of Terminal Alkenes by the Palladium/PhI(OPiv)₂ Catalyst System: Insights into the Effect of Naphthoquinone

Palladium-catalyzed oxidative amination of unactivated alkyl olefins has been developed to produce linear (E)-allylimides with high regioselectivity. This highly efficient transformation of alkenes has been achieved by enhancing the reoxidation of palladium with the strong oxidant PhI(OPiv)2. The present work also provides the first systematic analysis of the mechanism of the allylic C−H oxidative amination. It has been found that naphthoquinone (NQ) plays a vital role in promoting olefin coordination to the palladium catalyst: in the absence of NQ, the turnover-limiting step is olefin coordination to palladium catalyst; in the presence of NQ, the reaction involves a rapid equilibration to give a nitrogen-coordinated olefin-Pd(NQ) complex that undergoes turnover-limiting allylic C−H bond activation to generate a π-allyl-Pd intermediate. This work provides valuable insights for further studies on the functionalization of unactivated olefins

Photochemical Nickel-Catalyzed Reductive Migratory Cross-Coupling of Alkyl Bromides with Aryl Bromides

A novel method to access 1,1-diarylalkanes from readily available, nonactivated alkyl bromides and aryl bromides via visible-light-driven nickel and iridium dual catalysis, wherein diisopropylamine (^<i>i</i>Pr₂NH) is used as the terminal stoichiometric reductant, is reported. Both primary and secondary alkyl bromides can be successfully transformed into the migratory benzylic arylation products with good selectivity. Additionally, this method showcases tolerance toward a wide array of functional groups and the presence of bases

Stereoselective Palladium-Catalyzed 1,3-Arylboration of Unconjugated Dienes for Expedient Synthesis of 1,3-Disubstituted Cyclohexanes

As significant pharmacophores, 1,3-disubstituted cyclohexanes are widespread in natural products and synthetic bioactive molecules. In this work, we describe a palladium-catalyzed arylboration of 1,4-cyclohexadienes, which allows expeditious access to an array of functionalized 1,3-disubstituted cyclohexanes from the readily available starting materials. Palladium catalysis enables the arylboration to proceed in a reversed regioselectivity compared with earlier nickel catalysis. The most striking feature of this protocol lies in the 1,3-regioselectivity and exclusive cis-diastereoselectivity. Intriguingly, the success of this three-component reaction does not rely on the application of dative ligands but a cheap ammonium chloride salt instead. The synthetic utility of this method is highlighted by a series of downstream stereospecific transformations and a drug molecule synthesis

Stereoselective Palladium-Catalyzed 1,3-Arylboration of Unconjugated Dienes for Expedient Synthesis of 1,3-Disubstituted Cyclohexanes

As significant pharmacophores, 1,3-disubstituted cyclohexanes are widespread in natural products and synthetic bioactive molecules. In this work, we describe a palladium-catalyzed arylboration of 1,4-cyclohexadienes, which allows expeditious access to an array of functionalized 1,3-disubstituted cyclohexanes from the readily available starting materials. Palladium catalysis enables the arylboration to proceed in a reversed regioselectivity compared with earlier nickel catalysis. The most striking feature of this protocol lies in the 1,3-regioselectivity and exclusive cis-diastereoselectivity. Intriguingly, the success of this three-component reaction does not rely on the application of dative ligands but a cheap ammonium chloride salt instead. The synthetic utility of this method is highlighted by a series of downstream stereospecific transformations and a drug molecule synthesis

Stereoselective Palladium-Catalyzed 1,3-Arylboration of Unconjugated Dienes for Expedient Synthesis of 1,3-Disubstituted Cyclohexanes

As significant pharmacophores, 1,3-disubstituted cyclohexanes are widespread in natural products and synthetic bioactive molecules. In this work, we describe a palladium-catalyzed arylboration of 1,4-cyclohexadienes, which allows expeditious access to an array of functionalized 1,3-disubstituted cyclohexanes from the readily available starting materials. Palladium catalysis enables the arylboration to proceed in a reversed regioselectivity compared with earlier nickel catalysis. The most striking feature of this protocol lies in the 1,3-regioselectivity and exclusive cis-diastereoselectivity. Intriguingly, the success of this three-component reaction does not rely on the application of dative ligands but a cheap ammonium chloride salt instead. The synthetic utility of this method is highlighted by a series of downstream stereospecific transformations and a drug molecule synthesis

Asymmetric <i>anti</i>-Selective Borylalkylation of Terminal Alkynes by Nickel Catalysis

Selective transformation of alkyne triple bonds to double bonds serves as an efficient platform to construct substituted alkenes. While significant advances have been made in its spatiotemporal regulation, achieving a multicomponent enantioselective reaction that requires multifaceted selectivity issues to be overcome is still uncommon. Here, we report an unprecedented asymmetric anti-stereoselective borylcarbofunctionalization of terminal alkynes by nickel catalysis. The utilization of an inexpensive chiral diamine ligand enables the three-component cross-coupling of terminal alkynes, a diboron reagent, and prochiral alkyl electrophiles with high levels of regio-, stereo-, and enantioselectivities. This reaction provides an efficient protocol to access enantioenriched alkenyl esters bearing an α-stereogenic center, is remarkably practical, and has a broad scope and an outstanding functional group compatibility. In addition, the value of this method has been highlighted in a diversity of follow-up stereoretentive derivatizations and the stereoselective concise synthesis of complex drug molecules

Stereoselective Palladium-Catalyzed 1,3-Arylboration of Unconjugated Dienes for Expedient Synthesis of 1,3-Disubstituted Cyclohexanes

As significant pharmacophores, 1,3-disubstituted cyclohexanes are widespread in natural products and synthetic bioactive molecules. In this work, we describe a palladium-catalyzed arylboration of 1,4-cyclohexadienes, which allows expeditious access to an array of functionalized 1,3-disubstituted cyclohexanes from the readily available starting materials. Palladium catalysis enables the arylboration to proceed in a reversed regioselectivity compared with earlier nickel catalysis. The most striking feature of this protocol lies in the 1,3-regioselectivity and exclusive cis-diastereoselectivity. Intriguingly, the success of this three-component reaction does not rely on the application of dative ligands but a cheap ammonium chloride salt instead. The synthetic utility of this method is highlighted by a series of downstream stereospecific transformations and a drug molecule synthesis