Four N,O‐Bidentate‐Chelated Ligand‐Tunable Copper(II) Complexes: Synthesis, Structural Characterization and Exceptional Catalytic Properties for Chan–Lam Coupling Reactions

Abstract

Four N,O-bidentate chelating ligands [L 1 = N-(4thiazolylmethyl)morpholine-N-oxide, L 2 = N-(2-pyridylmethyl)pyrrolidine-N-oxide, L 3 = N-(4-thiazolylmethyl)pyrrolidine-Noxide, and L 4 = N-(2-pyridylmethyl)morpholine-N-oxide] were designed and synthesized. The treatment of N,O-bidentate ligands with CuCl 2 in ethanol at room temperature afforded four new copper complexes-[Cu(L 1 ) 2 ]Cl 2 ([Cu(L 4 ) 2 (CH 3 OH) 2 ][CuCl 4 ] 2 (IV)-which were fully characterized by single-crystal X-ray diffraction, IR spectroscopy and elemental analyses. Most interestingly,t he single-crystal Xray diffraction analyses revealed that the N,O-bidentate ligands L 1 -L 4 can tune the corresponding geometry configu-ration of coppera toms in complexes I-IV.T he copper atoms in I and II showed four-coordinated distorted squarep lanar geometry,w hereas the central coppera tom in III adopted a distorted square pyramidal geometry.I ts hould be noted that complex IV was constructed by ad istorteds quare planar CuN 2 O 2 unit, one octahedral CuN 2 O 4 unit and two [CuCl 4 ] 2À anions. Importantly,t hese copper(II) complexes, especially complex IV,s howedh igh catalytic activity in Chan-Lam coupling reactions of primary or secondary amines with arylboronic acid under mild conditions. Substrates with many functionalg roups were tolerated and the C-N coupling products were afforded in good to excellent yields (up to 96 %y ield).[a] Dr.

N‐(4‐Thiazolylmethyl)Morpholine N‐Oxide as N,O‐Bidentate Ligand for Copper‐Catalyzed Ullmann‐Type N‐Arylation of Azoles/Amines with Aryl Halides

“…Unless otherwise stated, the chemical materials were purchased from commercial sources and used directly. The ligands ( L 1 , L 2 ) were obtained from commercial suppliers and the ligands ( L 3 ‐ L 9 ) were synthesized according to our reported method . The coupling reactions were performed in resealable tubes with Teflon septa under an argon atmosphere and monitored by thin layer chromatography (TLC) analysis on GF‐254 silica gel.…”

The crystal structure of 13-ethoxycarbonyl-9-methyl-4-chlor-11-thioxo-8-oxa-10,12-diazatricyclo[7.3.1.02,7]trideca-2,4,6-triene, C14H15ClN2O3S

“…As we know, heterocyclic compounds containing N atoms exhibit important biological activities, pharmaceutical properties and the function of constructing metal complexes, etc. [3][4][5][6][7]. Among the N-heterocyclic compounds, 3,4-dihydropyrimidin-2-ones, 3,4-dihydropyrimidin-2-thiones compounds have been widely used in the field of antiviral [8], antitumor [9] and antibacterial activities [10].…”

Three copper(II) complexes derived from 2‐methylquinoline and cyclic secondary amines: Synthesis and catalytic application in C—N bond forming reactions

“…Recently, our group have achieved the controllable synthesis of four structurally diverse N , O ‐coordinated copper(II) complexes, which exhibited high catalytic activity in Chan–Lam coupling of arylboronic acids with amines or 1 H ‐imidazole derivatives. [ 33 ] The designed N , O ‐bidentate ligands also displayed their greater superiority than commercial available N , N ‐bidentate ligands (such as 2,2′‐bipyridine or 1,10‐phenanthroline) in copper(I)‐catalyzed Ullmann‐type coupling reaction between aryl halides and nitrogen‐containing substrates. [ 34 ] In order to further investigate the relation between the structure of N ‐oxide ligands and catalytic activity of formed copper complexes, we have synthesized three N , O ‐bidentate ligands derived from 2‐methylquinoline and cyclic secondary amines and prepared the corresponding copper complexes.…”