Mingzhong Cai

A phosphine-free carbonylative cross-coupling reaction of aryl iodides with arylboronic acids catalyzed by immobilization of palladium in MCM-41

The phosphine-free heterogeneous carbonylative cross-coupling of aryl iodides with arylboronic acids under an atmospheric pressure of carbon monoxide was achieved in anisole at 80 °C in the presence of a 3-(2-aminoethylamino)propyl-functionalized MCM-41-immobilized palladium(II) complex [MCM-41–2N–Pd(II)], yielding a variety of unsymmetrical biaryl ketones in good to high yield. This heterogeneous palladium catalyst exhibited higher activity and selectivity than PdCl2(PPh3)2, can be recovered and recycled by a simple filtration of the reaction solution, and used for at least 10 consecutive trials without any decrease in activity. Our system not only avoids the use of phosphine ligands, but also solves the basic problem of palladium catalyst recovery and reuse.

Recyclable and reusable PdCl2(PPh3)2/PEG-2000/H2O system for the carbonylative Sonogashira coupling reaction of aryl iodides with alkynes

PdCl2(PPh3)2 in a mixture of water and poly(ethylene glycol) (PEG-2000) is shown to be an extremely active catalyst for the carbonylative Sonogashira coupling reaction of aryl iodides with terminal alkynes. The reaction can be conducted under an atmospheric pressure of carbon monoxide at 25 °C with Et3N as a base, yielding a variety of alkynyl ketones in good to excellent yields. Application of this synthetic method to prepare flavones from o-iodophenol and terminal alkynes was also achieved. The isolation of the products is readily achieved by extraction with diethyl ether, and the PdCl2(PPh3)2/PEG-2000/H2O system can be easily recycled and reused six times without any loss of catalytic activity.

Recyclable and Reusable [RuCl2(p-cymene)]2/Cu(OAc)2/PEG-400/H2O System for Oxidative C-H Bond Alkenylations: Green Synthesis of Phthalides.

[RuCl2(p-cymene)]2 in a mixture of poly(ethylene glycol) (PEG-400) and water is shown to be an extremely efficient catalyst for the cross-dehydrogenative C-H bond alkenylation reaction between benzoic acids and alkenes. The reaction could be conducted at 80 °C using Cu(OAc)2·H2O as oxidant, yielding a variety of phthalide derivatives in good to excellent yields. More importantly, both [RuCl2(p-cymene)]2 and Cu(OAc)2 in the PEG-400/H2O system could be easily recycled and reused six times without any loss of catalytic activity.

Silica-supported bidentate arsine palladium(0) complex: a highly active and stereoselective catalyst for arylation of conjugated alkenes

A silica-supported bidentate arsine palladium(0) complex has been prepared from 4-oxa-6,7-dichloroheptyltriethoxysilane via immobilization on fumed silica, followed by reacting with potassium diphenylarsenide and palladium chloride, and then the reduction with hydrazine hydrate. The complex has been characterized by X-ray photoelectron spectroscopy and it is a highly active and stereoselective catalyst for arylation of styrene and acrylic acid with aryl halides affording a variety of trans-stilbenes and substituted trans-cinnamic acids in high yields.

Ruthenium(III) Chloride Catalyzed Acylation of Alcohols, Phenols, and Thiols in Room Temperature Ionic Liquids

Ruthenium(III) chloride-catalyzed acylation of a variety of alcohols, phenols, and thiols was achieved in high yields under mild conditions (room temperature) in the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]). The ionic liquid and ruthenium catalyst can be recycled at least 10 times. Our system not only solves the basic problem of ruthenium catalyst reuse, but also avoids the use of volatile acetonitrile as solvent.

Synthesis of indolyl imidazole derivatives via base-promoted tandem reaction of N-[2-(1-alkynyl)phenyl]carbodiimides with isocyanides.

An efficient route to indolyl imidazole derivatives has been developed through a base-promoted tandem reaction of N-[2-(1-alkynyl)phenyl]carbodiimides with isocyanides in DMSO at 40 °C. The present tandem process allows the assembly of a variety of indolyl imidazole derivatives in moderate to good yields.

Heterogeneous Hydrothiolation of Alkynes with Thiols Catalyzed by Diphosphino-Functionalized MCM-41 Anchored Rhodium Complex

A novel diphosphino-functionalized MCM-41 anchored rhodium complex [MCM-41-2P-RhCl(PPh3)] was conveniently synthesized by the reaction of diphosphino-functionalized MCM-41 (MCM-41-2P) with RhCl(PPh3)3. It was found that this rhodium complex is an efficient catalyst for the hydrothiolation of terminal alkynes with thiols and can be recovered and recycled by a simple filtration of the reaction solution and used for at least ten consecutive trials without any decreases in activity.Graphical AbstractThe diphosphino-functionalized MCM-41 anchored rhodium complex [MCM-41-2P-RhCl(PPh3)] is an efficient catalyst for the hydrothiolation of terminal alkynes with thiols and can be recovered and recycled by a simple filtration of the reaction solution and used for at least ten consecutive trials without any decreases in activity.

Synthesis of silica-supported poly-γ-diphenylarsinopropylsiloxane palladium complex and its catalytic behavior for Heck carbonylation of aryl halides

A silica-supported poly-γ-diphenylarsinopropylsiloxane palladium complex has been prepared from γ-chloropropyltriethoxysilane via immobilization on fumed silica, followed by reacting with potassium diphenylarsenide in THF and then the reaction with palladium chloride. It is an efficient catalyst for Heck carbonylation of aryl halides under atmospheric pressure of carbon monoxide. This polymeric palladium catalyst can be recovered and reused.

A highly efficient heterogeneous copper-catalyzed three-component coupling of tetrahydroisoquinolines, aldehydes and 1-alkynes

A highly efficient heterogeneous three-component coupling of tetrahydroisoquinolines, aldehydes and 1-alkynes was achieved in toluene at 70 °C in the presence of a 3-(2-aminoethylamino)propyl-functionalized MCM-41-supported copper(I) complex [MCM-41-2N–CuI], yielding a variety of C1-alkynylated tetrahydroisoquinolines (endo-yne-THIQs) in good to excellent yields with high regioselectivity. This heterogeneous copper catalyst can be easily prepared by a simple two-step procedure from commercially available and inexpensive reagents, and recovered by a simple filtration and reused for at least 10 times without any decrease in activity.

Phosphine-Free, Heterogeneous Palladium-Catalyzed Atom-Efficient Carbonylative Cross-Coupling of Triarylbismuths with Aryl Iodides: Synthesis of Biaryl Ketones

A novel and highly efficient heterogeneous palladium-catalyzed carbonylative cross-coupling of aryl iodides with triarylbismuths has been developed that proceeds smoothly at atmospheric CO pressure and provides a general and powerful tool for the preparation of various valuable biaryl ketones with high atom economy, good to excellent yield, and recyclability of the catalyst. The reaction is the first example of Pd-catalyzed carbonylative cross-coupling for the construction of biaryl ketones using triarylbismuths as substrates.