Trineopentylphosphine: A Conformationally Flexible Ligand for the Coupling of Sterically Demanding Substrates in the Buchwald–Hartwig Amination and Suzuki–Miyaura Reaction

Abstract

Trineopentylphosphine (TNpP) in combination with palladium provides a highly effective catalyst for the Buchwald-Hartwig coupling of sterically demanding aryl bromides and chlorides with sterically hindered aniline derivatives. Excellent yields are obtained even when both substrates include 2,6-diisopropyl substituents. Notably, the reaction rate is inversely related to the steric demand of the substrates. X-ray crystallographic structures of Pd(TNpP)2, [Pd(4-t-Bu-C6H4)(TNpP)(μ-Br)]2, and [Pd(2-Me-C6H4)(TNpP)(μ-Br)]2 are reported. These structures suggest that the conformational flexibility of the TNpP ligand plays a key role in allowing the catalyst to couple hindered substrates. The Pd/TNpP system also shows good activity for the Suzuki coupling of hindered aryl bromides.

Green Suzuki–Miyaura coupling reaction catalyzed by palladium nanoparticles supported on graphitic carbon nitride

“…4a, which can be expressed by the nonlinear form as follows: (1) where c a and c b (moldm -3 ) are the initial concentrations of phenylboronic acid and bromobenzene, c at and c bt (moldm -3 ) are the concentrations of phenylboronic acid and bromobenzene when reaction time is t, respectively. The reaction rate constants (k 2 , min -1 ) of various catalysts are shown in Fig.…”

“…The Pd-catalysed Suzuki-Miyaura coupling reaction has become a central tool for the construction of C-C bonds, widely used to synthesize natural products, non-natural products, and other bioactive compounds, as well as some advanced materials [1][2][3][4]. Traditionally, the C-C coupling reactions are carried out in organic solvents such as tetrahydrofuran and diethyl ether in the presence of Pd(II) or Pd(0) complexes having organic ligands at higher temperatures [5][6][7].…”

Bifunctional organic materials for OLEDs based on Tröger’s base: Subtle structural changes and significant differences in electroluminescence

“…Synthesis of 9-(N-phenylamino)anthracene [17]: An oven-dried pressure tube was cooled under nitrogen and charged with 9-bromanthracene (0.5 g, 1.9 mmol), distilled aniline (0.26 mL, 2.9 mmol), NaO t Bu (0.44 g, 3.8 mmol), Pd(OAc) 2 (22 mg, 5 mol%) and P( t Bu) 3 (23 lL, 0.1 mmol).…”

Tri(neopentyl)phosphine (TNpP)

“…A 90% yield of 2,4,6trimethylbiphenyl was obtained in the coupling of bromomesitylene with phenylboronic acid at room temperature using 1 mol % Pd(OAc) 2 /TNpP. 7 The TNpP-derived catalyst gave a 63% yield of 2,2 ,4,6-tetramethylbiphenyl from bromomesitylene and 2-tolylboronic acid (eq 3). The DTBNpP-derived catalyst gave only a 14% yield with these substrates.…”