Solvent-free Heck Reaction Research Articles

NHC-Pd(II) full pincer catalyzed Mizoroki-Heck Type Cross-Coupling of Vinyl Chloride and Alkenes: Synthesis of Novel Ferrocenylated Conjugated Dienes

This manuscript strives to establish a methodology for synthesizing new ferrocenylated conjugated dienes via a solvent-free Heck reaction of (2-formyl-1chlorovinyl) ferrocene/phenyl with vinyl arenes and acrylates by selanated NHC-Pd(II) full pincer complex. The complex was found to be highly efficient and robustly stable at high temperature and bring the desired coupling in quite instant time of 3 h under the solvent and inert-free condition. Apart from ferrocene derivatives, the reaction was found to be equally active for the β‑chloro cinnamaldehyde derivatives. Moreover, reaction shows high tolerance for all the functional groups and yields significant results with all variants of styrene, acrylate, while some unusual coupling with internal alkenes were also obtained.

An efficient and convenient copper catalyst system for the solvent-free Heck reaction

A novel 1-glycyl-3-methyl imidazolium chloride-copper(II) complex [[Gmim]Cl–Cu(II)] was found to be a heterogeneous catalyst for an efficient Heck reaction with good to excellent yield under solvent free condition. This protocol provides a simple strategy for the generation of a variety of new C–C bonds under environmentally benign condition. The catalyst was reused up to nine consecutive cycles without any significance loss in its activity.

Palladium supported on poly (ionic liquid) entrapped magnetic nanoparticles as a highly efficient and reusable catalyst for the solvent-free Heck reaction

A novel palladium catalyst supported on poly (1-aminoethyl-3-vinylimidazolium bromide) entrapped magnetic nanoparticles (Pd/Fe3O4@PIL-NH2) was prepared. The catalyst was characterized by TEM, FT-IR, VSM, XRD, and XPS. The Pd loading on the catalyst was 0.23wt% as measured by AAS. The catalyst showed excellent activity for the solvent-free Heck reaction. In addition, this novel Pd catalyst could be simply recovered with an external magnet and run five times with excellent yields achieved.

Immobilization of Pdnanoparticles with functional ionic liquid grafted onto cross-linked polymer for solvent-free Heck reaction

1-Aminoethyl-3-vinylimidazolium bromide ([VAIM]Br) grafted on the cross-linked polymer polydivinylbenzene (PDVB) was synthesized. The copolymers were used as a support to immobilize palladium nanoparticles. The catalyst was characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric (TG) analysis, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The catalytic performance of the copolymer-supported Pd nanoparticles for the Heck arylation of olefins with different aryl iodides was studied under solvent-free conditions. The results demonstrated that the catalyst was very active and stable under solvent-free conditions, and could be reused after simple separation. The reason for the high activity and stability of the catalyst is discussed.

Solvent-free Heck reaction catalyzed by a recyclable Pd catalyst supported on SBA-15 via an ionic liquid

Heck arylation of olefins with aryl halides was carried out in solvent-free conditions with a Pd catalyst supported on 1,1,3,3-tetramethylguanidinium (TMG)-modified molecular sieve SBA-15 (designated as SBA-TMG-Pd). SBA-TMG-Pd was much more active and stable than a Pd catalyst supported on pristine SBA-15 (designated as SBA-Pd). The catalysts were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM), and the reasons for the excellent performance of catalyst SBA-TMG-Pd were also discussed.

Enantioselective Rh-Catalyzed Hydrogenation of N-Formyl Dehydroamino Esters with Monodentate Phosphoramidite Ligands

Enantioselectivities up to >99% ee were achieved in the rhodium-catalyzed asymmetric hydrogenation of N-formyl dehydroamino esters using monodentate phosphoramidites as chiral ligands. The substrates were synthesized by condensation of methyl isocyanoacetate with a range of aldehydes and with cyclohexanone. A highly convenient multigram scale one step synthesis of methyl 2-(formamido)acrylate was developed. This compound was used in the synthesis of methyl 2-(formamido)cinnamate via a solvent free Heck reaction. Moreover, full conversion and >99% ee were obtained in 1 h in the hydrogenation of methyl 2-(formamido)acrylate with 0.2 mol % catalyst and 2 bar hydrogen pressure. The versatility of the formyl protection was established by its removal under mild conditions.

Phosphine ligands and nitrogen bases in the solvent-free Heck reaction of butenone with aryl iodides. A highly selective synthesis of benzalacetones

The solvent-free palladium-catalyzed reaction of butenone with aryl iodides has been studied. Phosphine ligands have been found to affect the vinylic substitution to hydroarylation (conjugate addition type) ratio. The nature of the nitrogen base also plays a role in controlling the product selectivity. In the presence of Pd(OAc)2, tris-(2,4,6-trimethoxyphenyl)phosphine and proton sponge the reaction affords exclusively vinylic substitution products usually in high to excellent yield.