Amine- and phosphine-free palladium(II)-catalyzed homocoupling reaction of terminal alkynes

An efficient, amine- and phosphine-free palladium(II)-catalyzed homocoupling of terminal alkynes has been developed. In the presence of PdCl₂, CuI, Me₃NO, and NaOAc, homocoupling of various terminal alkynes underwent smoothly to afford the corresponding diynes in moderate to high yields without any phosphine ligands. In contrast, the presence of a phosphine ligand (PPh₃) disfavored this palladium-catalyzed homocoupling procedure. Bases, solvents, and CuI have fundamental influence on the palladium-catalyzed homocoupling of terminal alkynes.     

Efficient Heck cross-coupling of 3-iodo-benzopyrones with olefins under microwave irradiation without phosphine

An efficient and effective microwave-assisted Heck cross-coupling of different terminal olefins with various 3-iodo-benzopyrones including sterically hindered, electron-rich, electron-neutral, and electron-deficient is developed. It proceeded faster and generally gave good to excellent yields under microwave irradiation, phosphine-free, and air condition. The reaction could render this method particularly attractive for the efficient preparation of biologically and medicinally interesting molecules.     

4-Amino-l,2,4-triazole Resin-supported Palladium Complex as Phosphine-free Catalyst for Suzuki Reaction in Aqueous Phase

1 Introduction The Suzuki cross-coupling reaction is a powerful and versatile method for the generation of unsymme-trical biaryls from arylboronic acids and aryl halides in a single step~([1-3]).However,the reaction is usually performed in the presence of Pd catalyst along with phosphine ligand,which sometimes creates practical problems because organophosphines tend to be expensive,poisonous,and air sensitive.Recently,phosphine-free ligands,such as nitrogen or sulfur-containing ligands~([4-6]) and N-heterocyclic car-benes~([7-12]) have been applied in Suzuki reaction effectively.     

1,3-Dicarbonyl compounds as phosphine-free ligands for Pd-catalyzed Heck and Suzuki reactions

Some 1,3-dicarbonyl compounds (such as pentane-2,4-dione and 3-oxo-N-phenylbutanamide) were found to constitute highly efficient, yet low-priced and phosphine-free ligands for the Pd-catalyzed Heck and Suzuki reactions of aryl bromides and iodides with very high turnover numbers (ca. 103-104).     

Regioselective Pd-catalyzed indolization of 2-bromoanilines with internal alkynes using phosphine-free ligands

The possibility of using phosphine-free ligands to promote Pd-catalyzed indolization of 2-bromoanilines with internal alkynes was examined for the first time. Phenylurea was found to be the optimal ligand, which could mediate the synthesis of 2,3-disubstituted indoles in good yields (ca. 60-85%) with high regioselectivity.     

Uridate/pyridyl Pd(II) complexes: Phosphine-free high turnover catalysts for the Heck reaction of deactivated aryl bromides

The synthesis and structure of palladium(II) complexes bearing uridato/pyridyl ligands as an anionic N-donor coordination sites are reported. The complexes have been shown to be highly active catalysts for the Heck reaction of aryl bromides (TON 4.0×10⁴-9.1×10⁴) and moderate activity for the activation of aryl chlorides under phosphine-free conditions.     

Phosphine-free Suzuki cross-coupling reaction: a mild and selective method for the carbon–carbon bond formation in aqueous tea extract

A mild and selective protocol has been developed for the palladium-catalyzed phosphine-free Suzuki cross-coupling reaction of aryl bromides with arylboronic acids in aqueous tea extract at room temperature. It is noteworthy that the aqueous tea extract plays an important role in the reaction, and various functional groups are tolerated under the optimized conditions. The reactions proceeded with very good chemoselectivity in favor of the bromo instead of the chloro group even at higher temperatures. Furthermore, this protocol could be applied to the cross-coupling of 4-bromoindole without protecting the base sensitive amine group with arylboronic acids in moderate to excellent yields.     

D301 resin as a solid base for phosphine-free Heck reactions with heteroaryl halides

A new and practical method of the D301 resin,a weak basic anion exchange resin with secondary amine functionality（Grade Matrix Structure：Styrene-DVB D301R）,used as base to Heck reactions catalyzed by palladium reagent without phosphine compound as ligand is described.It was found that the D301 resin used as base is an efficient and reusable base and can be regenerated and recycled in the reaction.The olefmation of heteroaryl halides prepared the corresponding products in good yields using D301 resin as base.     

1-苯基-3-甲基-4-苯甲酰基吡唑啉酮/PdCl2在温和条件下催化Suzuki偶联反应的研究

考察了商品化的简单非膦配体1-苯基-3-甲基-4-苯甲酰基吡唑啉酮在有氧温和条件下的Suzuki偶联反应活性,探讨了反应温度、反应时间、溶剂以及碱对反应的影响。结果表明,该配体在优化的反应条件下能高效催化不同溴代反应物和氯代反应物与苯硼酸的交叉偶联反应;提高反应温度、延长反应时间和引入质子性极性有机/水混合溶剂有利于偶联反应的进行。     

Advances in green colloidal synthesis of metal selenide and telluride quantum dots

This review summarized the green approaches toward colloidal chemical synthesis for metal selenide and telluride quantum dots.