Bis(pyrazolyl)methane Copper Complexes as Robust and Efficient Catalysts for Sonogashira Couplings

Abstract

A series of bis(pyrazolyl)methane copper complexes were found to catalyze a fast palladium‐free Sonogashira coupling reaction of several iodoarenes with terminal alkynes such as phenylacetylene, propargyl benzyl ether, and (tert‐butyl‐dimethyl)silylacetylene. These reactions proceed with CuCl2·2H2O (10 mol‐%) under aerobic conditions and the corresponding chelate ligand (10 mol‐%), with its tailored facial coordination mode, is crucial for the success of the reaction. The coupling can also be carried out in water with liquid aryl halides and a phase‐transfer catalyst.

One‐Pot Two‐Step Chemoenzymatic Cascade for the Synthesis of a Bis‐benzofuran Derivative

“…As a catalyst for this reaction, the complex [CuCl 2 {HC(Pz) 2 MeIm}] ({bis(pyrazolyl)(methyl imidazolyl)}‐methane copper(II) chloride) (catalyst 7 ) was selected. There are two main advantages for choosing this complex, on the one hand it was shown to be a highly active catalyst for the Sonogashira coupling . On the other hand the synthesis of this complex can be easily scaled up.…”

“…Copper(II) bis(pyrazolyl)methane complexes are highly active and robust catalysts for the palladium‐free Sonogashira coupling reaction. The reaction is performed under aerobic conditions in DMF . The Cu scorpionate‐mediated Sonogashira reaction protocol was successfully expanded to 2‐iodophenol ( 1 ) to perform a cascade Sonogashira coupling/cyclization reaction yielding 2‐substituted benzofurans (Scheme , benzofuran 3 ).…”

“…This is commonly performed in non‐aqueous solvents . Previously, we developed copper scorpionate complexes which are active Sonogashira catalysts in water . In principle this class of poly(pyrazolyl)methane copper complexes provides access to multiple catalytic reactions …”

Immobilization of copper complexes with (1,10-phenanthrolinyl)phosphonates on titania supports for sustainable catalysis

“…99,100 Commonly, this reaction is performed in anhydrous solvents in the presence of tertiary amines, palladium catalysts and with copper salts as co-catalysts. Palladium-free conditions were also widely explored 99,[101][102][103] but heterogenized copper complexes are still limited by a few examples. 47,[104][105][106][107] In the preliminary experiment, a model reaction of piodoanisole with phenylacetylene in toluene at 110 C was a The molar ratio was calculated from the Cu, P, and N content determined by elemental analysis and ICP-OES.…”

Greener and practical synthesis of 4,4′‐(arylmethylene)bis(3‐methyl‐1‐phenyl‐1H‐pyrazol‐5‐ol)s through a conventional heating and a mechanochemical procedure

“…They have been shown antimicrobial, 1 antiviral, 2 antitumor, 3 antioxidant, 4 and antibacterial, 5 activities, and they were used as selective COX‐2 inhibitors 6 and insecticides 7 . Bis(pyrazolyl)methane copper complexes used as a catalyst for Sonogashira couplings 8 . Their derivatives have been applied as extracting or chelating agents for a variety of metal ions 9,10 …”