Copper-Catalyzed Cross Dehydrogenative Coupling Reactions of Tertiary Amines with Ketones or Indoles

Selective Oxidation of Cyclohexane to Cyclohexanol/Cyclohexanone by Surface Peroxo Species on Cu-Mesoporous TiO2

Selective oxidation of cyclohexane to cyclohexanol/cyclohexanone (KA-oil) is an important chemical process, which is still constrained by low conversion and selectivity and high energy consumption. In this study, Cu-doped mesoporous TiO₂ (Cu-MT) has been successfully synthesized via calcinating MIL-125(Ti) doped with copper acetylacetonate, which shows high reactivity in selective oxidation of cyclohexane to KA-oil by persulfate (PS) with the desirable cyclohexane conversion of 16.8% and a selectivity of 98.0% under mild conditions and the low ratio of PS/cyclohexane of 1:1. A series of characterizations and density functional theory calculations reveal that the doped Cu(I,II) on Cu-MT is the reactive site for non-radical activation of PS with the moderate elongation of the O-O bond in PS, which then abstracts 1H (1H⁺ + 1e^-) from cyclohexane to form Cy^• and eventually KA-oil. This study gives new insight on the importance of moderately activated PS in selective oxidation of C-H.

Mechanistic insights into the rhodium–copper cascade catalyzed dual C–H annulation of indoles

Density functional theory (DFT) calculations have been performed to provide mechanistic insight into the Rh/Cu co-catalyzed multicomponent annulation of indoles, diazo compounds, and α,β-unsaturated esters.

Bimolecular oxidative C–H alkynylation of α-substituted isochromans

The first bimolecular oxidative C–H functionalization of secondary benzylic ethers for tertiary ether synthesis has been established in high efficiency.

Copper-Catalyzed Syntheses of Pyrene-Pyrazole Pharmacophores and Structure Activity Studies for Tubulin Polymerization

Tubulin polymerization is critical in mitosis process, which regulates uncontrolled cell divisions. Here, we report a new class of pyrene-pyrazole pharmacophore (PPP) for targeting microtubules. Syntheses of seven pyrenyl-substituted pyrazoles with side-chain modification at N-1 and C-3 positions of the pyrazole ring were accomplished from alkenyl hydrazones via C-N dehydrogenative cross-coupling using copper catalyst under aerobic condition. Tubulin polymerization with PPPs was investigated using docking and biological tools to reveal that these ligands are capable of influencing microtubule polymerization and their interaction with α-, β-tubulin active binding sites, which are substituent specific. Furthermore, cytotoxicity response of these PPPs was tested on cancer cells of different origin, such as MCF-7, MDA-MB231, and C32, and also noncancerous normal cells, such as MCF-10A. All newly synthesized PPPs showed excellent anticancer activities. The anticancer activities and half-maximal inhibitory concentration (IC₅₀) values of all PPPs across different cancer cell lines (MCF-7, MDA-MB231, and C32) have been demonstrated. 1,3-Diphenyl-5-(pyren-1-yl)-1H-pyrazole was found to be best among all other PPPs in killing significant population of all of the cancerous cell with IC₅₀ values 1 ± 0.5, 0.5 ± 0.2, and 5.0 ± 2.0 μM in MCF-7, MDA-MB231, and C32 cells, respectively.

Direct oxidative C-H alkynylation of N-carbamoyl tetrahydroisoquinolines and dihydroisoquinolines

An efficient oxidative C-H alkynylation of N-carbamoyl tetrahydroisoquinolines mediated by a TEMPO oxoammonium salt has been established. A variety of electronically varied N-carbamoyl tetrahydroisoquinolines reacted with a range of alkynyl potassium trifluoroborates smoothly under mild metal-free conditions. Dihydroisoquinolines were also suitable components for the reaction. The synthetic applicability of the method for facile access to structurally diverse bioactive molecules was further demonstrated.

Oxidative C(sp3)–H amidation of tertiary arylamines with nitriles

The first amidation of tertiary arylamines with nitriles via a cascade dehydrogenation/heterocoupling/addition reaction has been developed.

An unprecedented tandem synthesis of fluorescent coumarin-fused pyrimidines via copper-catalyzed cross-dehydrogenative C(sp3)–N bond coupling

A Cu-catalyzed tandem strategy for the synthesis of coumarin-fused pyrimidin-5-ones involving in situ intramolecular cross-dehydrogenative C(sp³)–N bond formation.

Oxidative C–H functionalization of N-carbamoyl 1,2-dihydroquinolines

A modular and efficient method for the synthesis of α-substituted 1,2-dihydroquinolines through an oxidative C–H functionalization strategy is described.

Cu(ii)-Mediated keto C(sp3)–H bond α-acyloxylation of N,N-dialkylamides with aromatic carboxylic acids

The first example of Cu(ii)-mediated oxidative coupling of aromatic carboxylic acids with the C(sp³)–H bond adjacent to the keto group of N,N-dialkylamides has been developed.

Cu(i)-Catalyzed oxidative homo-coupling of thiazoline-4-carboxylates: synthesis of 4,4′-bithiazoline derivatives

Cu(i)-Catalyzed oxidative homo-coupling of thiazoline-4-carboxylates with good functional group tolerance has been developed.

Copper catalyzed oxidative deamination of Betti bases: an efficient approach for benzoylation/formylation of naphthols and phenols

A copper-catalyzed benzoylation/formylation of naphthols and phenols via oxidative deamination of Betti bases.

A practical oxidative C–H functionalization of N-carbamoyl tetrahydro-β-carbolines with diverse potassium trifluoroborates

A practical and mild metal-free oxidative C–H functionalization ofN-carbamoyl tetrahydro-β-carbolines with diverse potassium trifluoroborates has been reported.

Cross-dehydrogenative regioselective Csp3–Csp2coupling of enamino-ketones followed by rearrangement: an amazing formation route to acridine-1,8-dione derivatives

A novel route for the construction of acridine-1,8-dione derivatives through CDC coupling of enamino-ketones followed by rearrangement.

Iminoiodane- and Brønsted base-mediated cross dehydrogenative coupling of cyclic ethers with 1,3-dicarbonyl compounds

A one-pot, two-step approach to prepare 2-tetrahydrofuran and -pyran substituted 1,3-dicarbonyl compounds by PhI=NTs-mediated amination/Brønsted base-catalyzed cross dehydrogenative coupling (CDC) reaction of the cyclic ether and 1,3-dicarbonyl derivative under mild conditions is reported. The reaction is compatible with a variety of cyclic ethers and 1,3-dicarbonyl compounds, affording the corresponding coupled products in moderate to good yields of up to 80% over two steps.

Friedel–Crafts reaction of indoles with vicinal tricarbonyl compounds generated in situ from 1,3-dicarbonyl compounds and TEMPO: highly selective synthesis of tertiary alcohols

A novel Friedel–Crafts reaction of indoles with vicinal tricarbonyl compounds generated in situ has been developed, forming indolyl tertiary alcohols. The process involves disproportionation of TEMPO, α-oxyamination, N–O bond cleavage and, finally, addition of the indole.

Iron-catalyzed aerobic C–H functionalization of pyrrolones

The aerobic oxidation of pyrrolones catalyzed by Fe(OTf)₃ to form reactive N-acyliminium ion intermediates that undergo nucleophilic additions to give the corresponding products is described.

Direct construction of 2-alkylbenzo-1,3-azoles via C–H activation of alkanes for C–C and C–X (X = O, S) bond formation

2-Alkylated benzo(oxa)thiazoles were prepared directly from simple alkanes and aryl isocyanates/isothiocyanates in a one-pot procedure.

Unexpected CN bond formation via NaI-catalyzed oxidative de-tetra-hydrogenative cross-couplings between N,N-dimethyl aniline and sulfamides

A direct de-tetra-hydrogenative cross-coupling reaction between C_sp3–H bonds and sulfamide under transition-metal-free conditions is reported to give the corresponding amidines.

Copper-catalyzed oxidative dimerizations of 3-N-hydroxy-aminoprop-1-enes to form 1,4-dihydroxy-2,3-diaminocyclohexanes with C2 symmetry

This work describes the one-step construction of complex and important molecular frameworks through copper-catalyzed oxidations of cheap tertiary amines. Copper-catalyzed aerobic oxidations of N-hydroxyaminopropenes to form C2 -symmetric N- and O-functionalized cyclohexanes are described. Such catalytic oxidations proceed with remarkable stereocontrol and high efficiency. Reductive cleavage of the two NO bonds of these products delivers 1,4-dihydroxy-2,3-diaminocyclohexanes, which are important skeletons of several bioactive molecules.

Copper catalyzed C-O bond formation via oxidative cross-coupling reaction of aldehydes and ethers

A practical and efficient construction of C-O bonds via oxidative cross-coupling reaction of aldehydes and ethers has been realized under open air. When 2 mol% copper was used as the catalyst, various α-acyloxy ethers were obtained with up to 93% isolated yield.