Cobalt-Catalyzed Hydroarylations and Hydroaminations of Alkenes in Tunable Aryl Alkyl Ionic Liquids

Abstract

Tunable aryl alkyl ionic liquids (TAAILs) are a promising class of imidazolium-or triazolium-based ionic liquids. Contrary to "standard" all-alkyl ionic liquids, these carry an aryl ring together with a linear or branched alkyl chain. Their application in the cobalt-catalyzed hydroarylation/hydroamination of alkenes and anilines is presented. The catalytic system is tolerant toward air and is scalable and reusable. It has been successfully used for the synthesis of pharmacologically relevant primary to tertiary aryl amines.

Earth-Abundant 3d Transition Metal Catalysts for Hydroalkoxylation and Hydroamination of Unactivated Alkenes

“…This successful merger of a photoredox cycle with Co-mediated HAT should open the door for further interesting developments in the rich chemistry of CoH-mediated oxidative hydrofunctionalization reaction. In 2018, with the aim of developing a Co-catalyzed direct hydroamination protocol with primary amines (and oxidant-free) and inspired by their previous Fe-catalyzed cyclohydroamination, [64] Ujaque, Lledós and Hannedouche developed a β-diketiminatocobalt(II) complex to promote the exo-cyclization of unprotected aminoalkenes under mild conditions (Figure 15) [98,99]. This report was the first example of cobalt-catalyzed hydroamination of primary amines.…”

“…This protocol allows the formation and isolation of diverse gem-disubstituted pyrrolidines and piperidines in good-to-high yields. However, it was unsuccessful for the cyclization of amines tethered to trisubstituted alkenes or substrates unbiased toward cyclization but suitable for primary amines bearing dimethyl- In 2018, with the aim of developing a Co-catalyzed direct hydroamination protocol with primary amines (and oxidant-free) and inspired by their previous Fe-catalyzed cyclohydroamination, [64] Ujaque, Lledós and Hannedouche developed a β-diketiminatocobalt(II) complex to promote the exo-cyclization of unprotected aminoalkenes under mild conditions (Figure 15) [98,99]. This report was the first example of cobalt-catalyzed hydroamination of primary amines.…”

Expanding the Electrochemical Window: New Tunable Aryl Alkyl Ionic Liquids (TAAILs) with Dicyanamide Anions

“…The reaction can be done in a6Lb atch reactoro nascale of up to 0.5 kg of aniline, yielding substituteda ryl imidazoles 1-4.T he follow- ing alkylation with different alkyl bromides gives TAAILs 5-16 with bromide counterion, synthesized as previouslyr eported by our group in multi-molar scale. [47] Anion exchange with lithium bis(trifluoromethylsulfonyl)imide (LiNTf 2 )a fforded the corresponding TAAILs 17-28.…”

Synthesis and Physical Properties of Tunable Aryl Alkyl Ionic Liquids (TAAILs)

“… [23] In 2009, 1‐aryl‐3‐alkyl‐imidazolium based ILs which we named tunable aryl alkyl ionic liquids (TAAILs) were introduced by our group. [24] Since then, their application in transition metal catalysis,[ 25 , 26 ] metal extraction[ 27 , 28 ] and for the synthesis of metal nano particles has been reported. [29] This new structural motive allows for the modification not only of its anion and alkyl substitution of the cation, but also by the aryl substitution giving rise to additional ways of controlling the physical and chemical properties of an ionic liquid.…”