Recycling Fe and improving organic pollutant removal via in situ forming magnetic core-shell Fe3O4@CaFe-LDH in Fe(II)-catalyzed oxidative wastewater treatment.

Due to its high efficiency, Fe(II)-based catalytic oxidation has been one of the most popular types of technology for treating growing organic pollutants. A lot of chemical Fe sludge along with various refractory pollutants was concomitantly produced, which may cause secondary environmental problems without proper disposal. We here innovatively proposed an effective method of achieving zero Fe sludge, reusing Fe resources (Fe recovery = 100%) and advancing organics removal (final TOC removal > 70%) simultaneously, based on the in situ formation of magnetic Ca-Fe layered double hydroxide (Fe3O4@CaFe-LDH) nano-material. Cations (Ca2+ and Fe3+) concentration (≥ 30 mmol/L) and their molar ratio (Ca:Fe ≥ 1.75) were crucial to the success of the method. Extrinsic nano Fe3O4 was designed to be involved in the Fe(II)-catalytic wastewater treatment process, and was modified by oxidation intermediates/products (especially those with COO- structure), which promoted the co-precipitation of Ca2+ (originated from Ca(OH)2 added after oxidation process) and by-produced Fe3+ cations on its surface to in situ generate core-shell Fe3O4@CaFe-LDH. The oxidation products were further removed during Fe3O4@CaFe-LDH material formation via intercalation and adsorption. This method was applicable to many kinds of organic wastewater, such as bisphenol A, methyl orange, humics, and biogas slurry. The prepared magnetic and hierarchical CaFe-LDH nanocomposite material showed comparable application performance to the recently reported CaFe-LDHs. This work provides a new strategy for efficiently enhancing the efficiency and economy of Fe(II)-catalyzed oxidative wastewater treatment by producing high value-added LDHs materials.

Kinetic Resolution of P-Chiral Phosphindole Oxides through Rhodium-Catalyzed Asymmetric Arylation.

Highly efficient kinetic resolution of P-chiral phosphindole oxides via rhodium-catalyzed asymmetric arylation under mild conditions is described. Selectivity factors of up to 569 were achieved by employing chiral diene* as a ligand. The transformation of the enantiopure benzophosphole derivative into a useful P-chiral bisphosphine ligand is also demonstrated.

Rhodium-Catalyzed Asymmetric Addition to 4- or 5-Carbonyl-cycloenones through Dynamic Kinetic Resolution: Enantioselective Synthesis of (-)-Cannabidiol.

The reaction of 4/5-carbonyl-cycloalkenone 1 or its achiral isomer 1' with organoboronic acid 2 in the presence of a chiral diene (S,S)-Fc-tfb-rhodium catalyst gave disubstituted trans-cycloalkanone 3 with high diastereo- and enantioselectivity. This highly efficient dynamic kinetic resolution is achieved by fast racemization of 1 through the formation of a dienolate followed by kinetic resolution with the chiral catalyst. The utility is demonstrated by the synthesis of key intermediates en route to (-)-cannabidiol.

Rhodium-Catalyzed Three-Component Reaction of Alkynes, Arylzinc Chlorides, and Iodomethanes Producing Trisubstituted/Tetrasubstituted Alkenes with/without 1,4-Migration.

A three-component reaction of alkynes, arylzinc chlorides, and iodomethanes was found to proceed in the presence of a rhodium catalyst to give high yields of trisubstituted/tetrasubstituted alkenes. The usual arylzinc chlorides only gave trisubstituted alkenes, generated through a migratory carbozincation-cross-coupling sequence, where 1,4-Rh migration from an alkenyl carbon to an aryl carbon occurred. In contrast, 5-membered heteroarylzinc chlorides only gave the tetrasubstituted alkenes via a carborhodation-cross-coupling pathway without 1,4-migration.

Vitamin B6 based Pt(II) complexes: biomolecule derived potential cytotoxic agents for thyroid cancer.

Vitamin B6 is an essential vitamin that serves as a co-enzyme in a number of enzymatic reactions in metabolism of lipids, amino acids, and glucose. In the current study, we synthesized vitamin B6 derived ligand (L) and its complex Pt(L)Cl (C1). The ancillary chloride ligand of C1 was exchanged with pyridine co-ligand and another complex Pt(L)(py).BF4 (C2) was obtained. Both these complexes were obtained in excellent isolated yields and characterized thoroughly by different analytical methods. Thyroid cancer is one of the most common malignancies of the endocrine system, we studied the in vitro anticancer activity and mechanism of these vitamin B6 derived L and Pt(II) complexes in thyroid cancer cell line (FTC). Based on MTT assay, cell proliferation rate was reduced in a dose-dependent manner. According to apoptosis analysis, vitamin B6 based Pt(II) complexes treated cells depicted necrotic effect and TUNEL based apoptosis was observed in cancer cells. Furthermore, qRT-PCR analyses of cancer cells treated with C1 and/or C2 showed regulated expression of anti-apoptotic, pro-apoptosis and autophagy related genes. Western blot results demonstrated that C1 and C2 induced the activation of p53 and the cleavage of Poly (ADP-ribose) polymerase (PARP). These results suggest that these complexes inhibit the growth of FTC cells and induce apoptosis through p53 signaling. Thus, vitamin B6 derived Pt(II) complexes C1 and C2 may be potential cytotoxic agents for the treatment of thyroid cancer.

Rhodium-Catalyzed Desymmetric Arylation of γ,γ-Disubsituted Cyclohexadienones: Asymmetric Synthesis of Chiral All-Carbon Quaternary Centers.

The desymmetric arylation of prochiral cyclohexadienones with ArZnCl in the presence of an (R)-segphos-rhodium catalyst gave high yields of the corresponding cyclohexenones, which contain a chiral arylated carbon center at the ß-position and a chiral all-carbon quaternary center at the γ-position, with high diastereo- and enantioselectivities. This catalytic system was also applied to the arylation of spirocarbocyclic cyclohexadienones and afforded the corresponding cyclohexenones bearing a chiral spiro quaternary carbon with high dr and ee.

Asymmetric Synthesis of Chiral Bicyclo[2.2.1]hepta-2,5-diene Ligands through Rhodium-Catalyzed Asymmetric Arylative Bis-cyclization of a 1,6-Enyne.

A series of novel chiral diene ligands (1R,4S)-L1, which are based on the bicyclo[2.2.1]heptadiene skeleton and are substituted with methyl and an ester group at the bridgehead carbons, were synthesized through rhodium-catalyzed asymmetric arylative bis-cyclization of 1,6-enyne 1 as a key step. The rhodium catalyst with one of the (1R,4S)-L1 ligands was used for the asymmetric bis-cyclization of 1 giving bicyclic product (1S,4R)-2 of 99% ee, which is a synthetic precursor of (1S,4R)-L1 ligands.

Room temperature cupric halides mediated olefin alkoxylation of BODIPYs with methanol: mechanisms and scope.

We disclose an efficient methodology for olefin alkoxylation of fluorescent BODIPYs (boron-dipyrromethene) at the 3,5-styryl group with methanol by cupric halide (chloride or bromide) at room temperature. Mechanistic studies provide evidence for the alkoxylation reaction firstly initiated by a radical cation, that is, halide promotes the oxidizing ability of the Cu(ii) center to an extent that the single electron transfer (SET) from BODIPYs to the cupric ion and results in the production of a BODIPYs radical cation and Cu(i), then the BODIPYs radical cation subsequently reacts with methanol to afford the alkoxylated product. As the dialkoxylated product complexes with cuprous halide and further decreases its reducing ability, which is supported by DFT calculations, only strongly oxidative cupric bromide can mediate tetraalkoxylation and give rise to the tetraalkoxylated product. In addition, the expanded scope studies suggest that this method is also well suited for the alkoxylation of electron-rich conjugated olefins. The active benzyl bromide derivative may be another intermediate in the presence of cupric bromide. Therefore, the reaction is highly dependent on the anions of cupric salts; Cu(OAc)2, CuSO4 and Cu(NO3)2 containing weakly nucleophilic anions show no activity in alkoxylation.

Addition of arylstannanes to alkynes giving ortho-alkenylarylstannanes catalysed cooperatively by a rhodium complex and zinc chloride.

The reaction of arylstannanes ArSnR3 with unfunctionalised alkynes was found to proceed in the presence of a rhodium catalyst and a catalytic amount of zinc chloride to give ortho-alkenylarylstannanes with high selectivity in high yields. The catalytic cycle is very unique, consisting of three transmetalation steps, from Sn to Rh, Rh to Zn, and Zn to Sn, in addition to arylrhodation of alkyne followed by 1,4-migration of Rh from 2-arylalkenyl carbon to ortho-alkenylaryl carbon.

Rhodium-Catalyzed Arylzincation of Alkynes: Ligand Control of 1,4-Migration Selectivity.

The addition of arylzinc reagents ArZnCl 1 to alkynes 2 was found to be catalyzed by rhodium complexes in the presence of a catalytic amount of zinc chloride. The selectivity in giving 2-arylalkenylzinc species 3 or ortho-alkenylarylzinc species 4, the latter of which is generated through 1,4-Rh migration from alkenyl to aryl in the catalytic cycle, is controlled by the ligands on rhodium. Ligands cod and binap gave 3 and 4, respectively, with high selectivity.

Aryloxymethyltrifluoroborates for Rhodium-Catalyzed Asymmetric Conjugate Arylation. o-Methoxyarylation through 1,4-Rhodium Shift.

Reaction of potassium aryloxymethyltrifluoroborates 1 with α,ß-unsaturated carbonyl compounds 2 in the presence of a chiral diene-rhodium catalyst in H2O at 100 °C introduced 2-methoxyaryl groups at the ß-position of 2 with high enantioselectivity in high yields. The reaction is assumed to proceed through 1,4-Rh shift from aryloxymethyl-Rh intermediate to 2-methoxyaryl-Rh. The high availability of phenol derivatives makes this asymmetric conjugate arylation synthetically useful.

Pillar[5]arene-based diglycolamides for highly efficient separation of americium(III) and europium(III).

Pillar[5]arenes, as a new intriguing class of calixarene analogues, were functionalized with ten diglycolamide (DGA) arms on both sides (rims) of the pillar framework and evaluated for their extraction behaviour towards Am(III) and Eu(III). These novel extractants exhibit excellent separation and extraction efficiency, suggesting its significant potential for nuclear waste remediation. Laser induced fluorescence experiments disclosed strong complexation of the trivalent metal ions with the pillararene-DGA ligands.