Application of Cyclopalladated Compounds as Catalysts for Heck and Sonogashira Reactions

Nájera, Carmén; Alonso, Diego A.

doi:10.1002/9783527623211.ch8

Cited by 9 publications

(4 citation statements)

References 165 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The one-and two-dimensional 1 H and 13 C NMR spectra were recorded at 25 • C in DMSO-d 6 and/or in CD 2 Cl 2 and CDCl 3 with Bruker AV-600 spectrometer operating at 600.13 MHz for the 1 H and 150.90 MHz for the 13 C resonances. 1 H and 1 H-1 H COSY spectra were recorded at 25, 0 and -25 7.9,7.7 Hz),7.74,d',3 J(HH) = 6.5, 6.5 Hz), 7.95, 9.12 d (H-e,e', 3 J(HH) = 5.9, 5.7 Hz). UV-vis (CHCl 3 ) l max /nm (e/10 4 M -1 cm -1 ): 306 sh (1.82), 315 (1.98), 340 (1.27), 378 (1.30), 469 (0.17), 498 (0.15).…”

Section: Experimental General Measurementsmentioning

confidence: 99%

“…Recently, considerable effort has been focused to the design and synthesis of cyclopalladated complexes containing N-donor ligands because of their potential application as model compounds for photoactive units in different optical devices, 1 as differential chromogenic and fluorescent chemosensors 2 as well as liquid crystalline materials and catalysts. 3 In this regard, particularly interesting are complexes with azobenzenes, due to their easy ortho-metallation by Pd(II) salts as well as to their structural and photophysical properties. 2e, 4 Azobenzene and its derivatives readily undergo reaction with Pd(II) convenient precursors to produce single or double cyclopalladated complexes containing one 5 or two metalacycles.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Unusual azobenzene/bipyridine palladacycles: structural, dynamical, photophysical and theoretical studies

et al. 2010

View full text Add to dashboard Cite

Two types of Pd(ii) azobenzene/bipyridine complexes with unusual coordination mode of azobenzenes, PdCl{(mu-Cl)(mu-R(1)C(6)H(3)N=NC(6)H(3)R(2))}Pd(bpy) 1a-4a and [(bpy)PdCl(mu-NH(2)C(6)H(3)N=NC(6)H(4))Pd(bpy)]Cl 3b were formed by the reaction of dicyclopalladated azobenzenes (DMF)PdCl(mu-R(1)C(6)H(3)N=NC(6)H(3)R(2))PdCl(DMF) with excess of bpy, where bpy=2,2'-bipyridine; R(2)=H and R(1)=H (1), CH(3) (2), NH(2) (3) or R(1)=N(CH(3))(2) and R(2)=NO(2) (4). Neutral species 1a-4a were obtained in acetone, while in DMSO or MeOH the ionic complex 3b was produced. When dissolved, 3b decomposes to 3a and free bpy; however in DMSO upon addition of bpy 3b crystallizes again. X-ray structures of all complexes confirmed breaking of one Pd-N bond in the initial precursors, thus allowing rotation of one phenyl ring and positioning of both Pd atoms on the same side of the azobenzene ligand. Two Pd atoms are connected by the azobenzene ligand and in neutral complexes additionally by the Cl-bridge. In all complexes in the solid-state azobenzenes act simultaneously as monodentate C- and bidentate C,N-donors while bpy acts as bidentate donor. Variable-temperature (1)H NMR experiments established that structures of 1a-4a in DMF and DMSO at ambient temperature are not consistent with solid-state structures due to the fast exchange of one of the bpy nitrogen atoms bound to the Pd atom with solvent molecules. Theoretical studies confirmed the experimental structures as the most stable isomers. Photoabsorption and photoemission properties of the new complexes have been measured and photoabsorption is rationalized by time dependent DFT calculations. The presence of bpy significantly increases the intensity of fluorescence either in the solution (4a) or in the solid state (3a, 4a, 3b) at ambient temperature.

show abstract

Section: Experimental General Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Unusual azobenzene/bipyridine palladacycles: structural, dynamical, photophysical and theoretical studies

et al. 2010

View full text Add to dashboard Cite

show abstract

“…Palladium-catalyzed Sonogashira coupling has been extensively investigated and enormous modifications of those catalyst systems have been made since the first report of Sonogashira coupling. This includes the employment of a variety of new cata-lyst systems (including tailor-made Pd-phosphines, [8] Pd-NHCs, [9] palladacycles, [10] Pd-nanoparticles and polymer-supported Pd catalysts, etc.) with unique additives and solvents.…”

Section: Introductionmentioning

confidence: 99%

Recent Expedition inPd‐CatalyzedSonogashira Coupling and Related Processes^†

2023

View full text Add to dashboard Cite

Sonogashira cross-coupling protocol, typically showing the reaction between aryl/vinyl halide and terminal alkyne, has been a widely used protocol for constructing C(sp 2 )-C(sp) bond. The resulting internal alkynes are highly versatile for reaching differently functionalized alkyne-containing scaffolds or serving as valuable synthetic synthons to many other functional groups. It is worth noting that products originated from this coupling reaction are mostly applicable to be transformed into corresponding Z-alkene, alkane, or heterocyclic moieties in natural product syntheses. The reaction conditions and catalyst systems are able to be tweaked in order to facilitate the activation of steric hindered and/or electron-rich electrophiles. Pd-catalyzed copper-free Sonogashira coupling reaction has caught increasing attention as the improved method can be more environmentally friendly. What is more, the conditions of the coupling reaction can be readily amended to allow the fusion of other carbonylation or decarboxylation step in the catalytic cycle, and thus allow more complex yet versatile convergent synthesis to proceed in an operationally simple one-pot manner.

show abstract

“…Nonpalladacycles, such as catalysts prepared from di-tertbutylphosphinoferrocene or QPhos (L4) in combination with Pd 2 (dba) 3 , have also shown to be excellent performers of the Heck reaction. 49,50 Despite the considerable research effort that has been put into developing the MHR, 5,6,9,13,51 there is an obvious lack of examples in literature that broadly describes the cross-coupling of electron-rich heteroaryl halides, unactivated olefins, or substrates that contain unprotected functional groups. These compounds are of particular importance as they resemble fragments that are frequently used by the specialty chemicals and pharmaceutical industries; however, they are often recalcitrant in catalysis.…”

Section: ■ Introductionmentioning

confidence: 99%

Palladium-meta-Terarylphosphine Catalyst for the Mizoroki–Heck Reaction of (Hetero)Aryl Bromides and Functional Olefins

et al. 2015

View full text Add to dashboard Cite

The evolutionary meta-terarylphosphine ligand architecture of Cy*Phine was recently shown to be a key feature that imposed outstanding performance in palladium-catalyzed copper-free Sonogashira applications. Herein, the Pd-Cy*Phine combination has similarly proven to be a powerful catalyst system for the Mizoroki-Heck reaction. Using high-throughput screening (HTS) methodology, DMF and NaHCO3 were rapidly identified as the most effective solvent and base pair for the cross-coupling catalysis of challenging and industrially valuable substrates including highly electron-rich heteroaryl bromides and unactivated olefins. Unprotected functional groups were well tolerated using low catalyst loadings, and the simple protocol produced excellent yields (up to 99%) with unprecedented substrate diversity. The Pd-Cy*Phine system broadly outperformed many state-of-the-art commercial alternatives, which demonstrated its potential as a next-generation cross-coupling catalyst.

show abstract

Application of Cyclopalladated Compounds as Catalysts for Heck and Sonogashira Reactions

Cited by 9 publications

References 165 publications

Unusual azobenzene/bipyridine palladacycles: structural, dynamical, photophysical and theoretical studies

Unusual azobenzene/bipyridine palladacycles: structural, dynamical, photophysical and theoretical studies

Recent Expedition inPd‐CatalyzedSonogashira Coupling and Related Processes^†

Palladium-meta-Terarylphosphine Catalyst for the Mizoroki–Heck Reaction of (Hetero)Aryl Bromides and Functional Olefins

Contact Info

Product

Resources

About

Application of Cyclopalladated Compounds as Catalysts for Heck and Sonogashira Reactions

Cited by 9 publications

References 165 publications

Unusual azobenzene/bipyridine palladacycles: structural, dynamical, photophysical and theoretical studies

Unusual azobenzene/bipyridine palladacycles: structural, dynamical, photophysical and theoretical studies

Recent Expedition inPd‐CatalyzedSonogashira Coupling and Related Processes†

Palladium-meta-Terarylphosphine Catalyst for the Mizoroki–Heck Reaction of (Hetero)Aryl Bromides and Functional Olefins

Contact Info

Product

Resources

About

Recent Expedition inPd‐CatalyzedSonogashira Coupling and Related Processes^†