Palladium-Catalyzed Amination of Aryl Nonaflates

Abstract

The first detailed study of the palladium-catalyzed amination of aryl nonaflates is reported. Use of ligands 2-4 and 6 allows for the catalytic amination of electron-rich and -neutral aryl nonaflates with both primary and secondary amines. With use of Xantphos 5, the catalytic amination of a variety of functionalized aryl nonaflates resulted in excellent yields of anilines; even 2-carboxymethyl aryl nonaflate is effectively coupled with a primary alkylamine. Moderate yields were obtained when coupling halo-aryl nonaflates with a variety of amines, where in most cases the aryl nonaflate reacted in preference to the aryl halide. Overall, aryl nonaflates are an effective alternative to triflates in palladium-catalyzed C-N bond-forming processes due to their increased stability under the reaction conditions.

Palladium‐Catalyzed CN and CO Coupling–A Practical Guide from an Industrial Vantage Point†

“…Cs 2 CO 3 is most effective when chelating bisphosphine ligands are used and many transformations using this base have been reported recently. [15,26 -28,30,31,33,51 -63] K 3 PO 4 tends to show good results with biphenyl-based systems [5,15,48,49] and P(t-Bu) 3 but is less useful with chelating ligands, which seems to be a general trend. [7] Recently, Hartwig and Buchwald even reported the use of the most inexpensive bases (KOH, NaOH) in aqueous solution which are active in combination with biphenyl-based systems as well as Hartwigs palladium-dimer complex.…”

“…Regarding the temperature, usually a range between room temperature for the most active ligand systems such as P(t-Bu) 3 , [46] some biphenyl-based systems [15,48] and carbenes [20,23] up to 140 8C for palladacyclic complexes [5,41] is reasonable. The vast majority of reactions is run inside a range of 70 -110 8C which can be considered as typical for biphenyl-based ligands.…”

“…When phenols are transformed to highly activated sulfonic acid esters like trifluoromethanesulfonic acid esters (triflates) or nonafluorobutanesulfonic acid esters (nonaflates), the coupling reaction runs with ease. [15,48,78,87,80] However, the industrial chemist will be less prone to reduce these systems to practice, since fluorinated sulfonic acid esters are very expensive in their use and disposal. Therefore a milestone in the use of phenol-derived starting materials was the first description of using the cheap sulfonic acid ester, p-toluenesulfonic acid ester, as starting material for aromatic amination by the Hartwig group [96] and the further elaboration of a more general protocol by the Buchwald group.…”

“…[20] Even broader applicability and generally higher catalytic activity can be attributed to Buchwalds biphenylphosphine family, which allows for room temperature reactions using aryl chlorides, bromides or iodides, but also for the use of nonaflates and triflates. [15,48] Hartwigs dimeric palladium(I)-P(tBu) 3 complex does not only represent a very elegant form of an air-stable P(t-Bu) 3 -type catalyst, it also proved to be extremely valuable for the room temperature amination of aryl bromides and chlorides, with complete formation of product within 15 minutes in some cases.…”

Pentavalent Organoantimony Compounds as Mild N-Arylating Agents for Amines: Cu-Mediated Ullmann-Type N-Arylation with Tetraarylantimony(V) Acetates

“…3,4) These transition metal-catalyzed reactions have been recognized as one of the most reliable methods for C-N bond formation. [5][6][7][8] Direct C-H functionalization to form C-N bonds has also been another convenient entry for C-N cross-coupling using transition metal catalysts. 9,10) However, these elaborated catalysts and phosphine ligands often tend to be sensitive to air oxidation and hydrolysis by moisture.…”