Thioether-Directed NiH-Catalyzed Remote γ-C(sp³)–H Hydroamidation of Alkenes by 1,4,2-Dioxazol-5-ones

Abstract

A NiH-catalyzed thioether-directed cyclometalation strategy is developed to enable remote methylene C–H bond amidation of unactivated alkenes. Due to the preference for five-membered nickelacycle formation, the chain-walking isomerization initiated by the NiH insertion to an alkene can be terminated at the γ-methylene site remote from the alkene moiety. By employing 2,9-dibutyl-1,10-phenanthroline (L4) as the ligand and dioxazolones as the reagent, the amidation occurs at the γ-C­(sp3)–H bonds to afford the amide products in up to 90% yield (>40 examples) with remarkable regioselectivity (up to 24:1 rr).

Enantioselective synthesis of α-aminoboronates by NiH-catalysed asymmetric hydroamidation of alkenyl boronates

“…This strategy is general and reliable and a large variety of electrophiles can be employed as coupling partners, which allows the stereochemically controlled formation of a variety of carbon–carbon 36 – 55 and carbon–heteroatom 56 – 65 bonds. Very recently, Seo and Chang 60 , 64 , Yu 63 , and our group 61 have demonstrated that dioxazolones are suitable electrophilic amidating reagents in NiH-catalysed reductive hydroamidation reactions. We envisioned that NiH-catalysed asymmetric hydrofunctionalization could be expanded to the asymmetric hydroamidation of alkenyl boronates with dioxazolones 30 , 60 – 64 , thus enabling the direct synthesis of a variety of enantioenriched α-aminoboronates which have high potential in medicinal chemistry.…”

Regioselective 1,2-carbosulfenylation of unactivated alkenesviadirected nickel catalysis

“…However, several challenges appeared considerably daunting: (1) undesired competitive cross-coupling between arylboron and electrophilic thiolation reagents, 16 (2) competitive β-H elimination from the alkyl nickel species, and (3) catalyst deactivation caused by sulfur coordination. 17 Herein, we report a Ni-catalyzed regioselective 1,2-carbosulfenylation of homoallylic amines with arylboronic acids and aryl disulfides under the assistance of bidentate PA auxiliary. This new protocol exhibits excellent functional group tolerance and is compatible with α-substituted terminal alkenes and internal alkenes.…”

“…However, several challenges appeared considerably daunting: (1) undesired competitive cross-coupling between arylboron and electrophilic thiolation reagents, 16 (2) competitive β-H elimination from the alkyl nickel species, and (3) catalyst deactivation caused by sulfur coordination. 17…”

Nickel‐Catalyzed Switchable Site‐Selective Alkene Hydroalkylation by Temperature Regulation**

“…Based on precedents, Lu and Fu reported an aminoquinoline directed nickel‐catalyzed alkene hydroalkylation, and adjustments to the reaction ligands resulted in the switching on and off of alkylnickel chain‐walking [11] . In addition, regiodivergent alkene hydroamination/hydroamidation by the chain‐walking of a nickel‐hydride species has also been realized, and ligand‐controlled regiodivergence is state of the art [5b, 12] …”