The Trifluoromethanesulfonanilide Class of Herbicides and Plant Growth Regulators

Fridinger, T. L.

doi:10.1016/b978-0-08-023930-9.50071-x

Cited by 1 publication

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“…4 Moreover, the use of weak organic bases avoids functional group incompatibility issues associated with nucleophilic alkoxide and metal amide bases, especially in combination with amines. 5 Previously, several phosphazene, 6 guanidine, 6 amidine, 7 and alkyl amine 8 bases have been shown to facilitate Pd-and Cu-catalyzed 9 C-N bond formation. The weakest among these, alkyl amine bases stand out as an attractive class of reagents, particularly since their steric properties, nucleophilicity, and basicity can be precisely tuned.…”

Section: Introductionmentioning

confidence: 99%

The Quest for the Ideal Base: Rational Design of a Nickel Precatalyst Enables Mild, Homogeneous C–N Cross-Coupling

Liu

Dennis²,

Buchwald³

2020

Preprint

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Palladium-catalyzed amination reactions using soluble organic bases have provided a solution to the many issues associated with heterogeneous reaction conditions. Still, homogeneous C–N cross-coupling approaches cannot yet employ bases as weak and economical as trialkylamines. Furthermore, organic base-mediated methods have not been developed for Ni(0/II) catalysis, despite some advantages of such systems over analogous Pd-based catalysts. We designed a new air-stable and easily prepared Ni(II) precatalyst bearing an electron-deficient bidentate phosphine ligand that enables the cross-coupling of aryl triflates with aryl amines using triethylamine (TEA) as base. The method is tolerant of sterically-congested coupling partners, as well as those bearing base- and nucleophile-sensitive functional groups. With the aid of density functional theory (DFT) calculations, we determined that the electron-deficient auxiliary ligands decrease both the pKa of the Ni-bound amine and the barrier to reductive elimination from the resultant Ni(II)–amido complex. Moreover, we determined that precluding Lewis acid-base complexation between the Ni catalyst and the base, due to steric factors, is important for avoiding catalyst inhibition.

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