Ligand‐Enabled Nickel‐Catalyzed Redox‐Relay Migratory Hydroarylation of Alkenes with Arylborons

Abstract

A redox‐relay migratory hydroarylation of isomeric mixtures of olefins with arylboronic acids catalyzed by nickel complexes bearing diamine ligands is described. A range of structurally diverse 1,1‐diarylalkanes, including those containing a 1,1‐diarylated quaternary carbon, were obtained in excellent yields and with high regioselectivity. Preliminary experimental evidence supports the proposed non‐dissociated chainwalking of aryl‐nickel(II)‐hydride species along the alkyl chain of alkenes before selective reductive elimination at a benzylic position. A catalyst loading as low as 0.5 mol % proved to be sufficient in large‐scale synthesis while retaining high reactivity, highlighting the practical value of this transformation.

Air‐Stable PdI Dimer Enabled Remote Functionalization: Access to Fluorinated 1,1‐Diaryl Alkanes with Unprecedented Speed

“…While there has been impressive progress in recent years in this context, [1,3] the current methodological repertoire to access 1,1-diaryl alkanes via such a remote functionalization strategy [4] requires relatively long reaction times (12-48 hours) and is limited in the substitution pattern; the vast majority of methods do not showcase the compatibility with orthosubstituents in these 1,1-diaryl alkanes. [5] In this context Baudoin recently reported a notable advance which relied on Pd-catalysis and could tolerate ortho-substituents, albeit requiring high temperatures (120 8C) during 48 hours and a terminal blocking group in the substrate to prevent alternative products (see Figure 1 B). [6,7] Ortho-fluorinated 1,1-diaryl alkane motifs were not showcased.…”

Ligand‐Enabled Nickel‐Catalyzed Redox‐Relay Migratory Hydroarylation of Alkenes with Arylborons

“…By treating Ni(OTf) 2 and L1 in methanol, adark yellow air-stable solid Ni(OTf) 2 •(L2) 2 was obtained. [14] Accordingly,with 0.5 mol %loading of this stable precatalyst, the standard reaction on 10 mmol-scale also proceeds well. Further experiments were conducted to assess the reactivity of different olefins.A ss hown in Scheme 1b,c ompetition experiments indicate that terminal alkenes are more reactive than internal alkenes.…”

Nickel-Catalyzed Regio- and Enantioselective Hydroarylation of 1,3-Dienes with Indoles

“…Substrates with a remote aromatic ring (3y, 3z, 3aa) or heteroaromatic ring (3w, 3x) worked well; no products resulted from olefin migration to the benzyl position and subsequent hydroarylation were detected. 38,39 In addition, this hydroarylation reaction could be used for late-stage modification of a structurally complex molecule bearing multiple stereocenters (87% yield, 97:3 dr, 3ab). It is worth mentioning that highly conjugated polyene substrate also underwent regioselective hydroarylation, affording product with a diene moiety 3ac.…”