Chain Extension of Piperazine in Ethanol: Synthesis of 2-(4-(2-(Phenylthio)ethyl)piperazinyl)acetonitriles and ACAT-1 Inhibitors.

A base-induced synthesis of 2-(4-(2-(phenylthio)ethyl)piperazinyl) acetonitriles by reaction of disulfides, 1-(chloromethyl)-4-aza-1-azonia bicyclo[2.2.2]octane chloride and trimethylsilyl cyanide is reported.

Direct transformation of nitriles to cyanide using chloride anion as catalyst.

A simple method is explored for the scission of C-CN bonds into aldehyde and CN in air. The transformation was mediated by chloride anions. The cyanide anions were extracted from the reaction solution to form (EtN)[Zn(CN)] and (EtN)[Ni(CN)].

Iodine-Mediated Heterocyclization for the Synthesis of 6-Alkylthio-1,3,5-triazine-2,4-diamines from -Alkylpyridinium Salts and NHSCN.

An iodine-mediated method for the synthesis of 6-alkylthio-1,3,5-triazine-2,4-diamines by the reaction of -alkylpyridinium salts and NHSCN in air is reported. Twenty-seven compounds were obtained under the standard conditions. Pyridinium salts work as benzyl-group transfer reagents to promote the formation of the C-S bond and thereby the construction of the triazine skeleton.

π-Extension of Indoles Using Acrolein Linker: Synthesis of Indolo[3,2-]carbazole-6-carbaldehydes and Racemosin B.

A simple method for the synthesis of indolo[3,2-]carbazole-6-carbaldehydes by the π-extension of indoles with acrolein is reported. The scope of the method is demonstrated with 33 examples. The products exhibit high activities toward advanced synthesis and are proved to be able to produce valuable chemicals, such as natural products, dyes, and organic fluorescent materials.

Copper-Catalyzed Oxidative [3 + 2] Cycloaddition of -Alkyl Pyridinium Salts to Imidazo[1,2-]pyridines.

A copper-catalyzed reaction of pyridinium salts and trimethylsilyl cyanide (TMSCN) in the presence of diethyl phosphite is developed. This reaction, which allows the single-step construction of biologically important 2-cyanoimidazo[1,2-]pyridine from readily available starting materials, is realized for the first time and is feasible at the gram scale. The scope of the protocol is demonstrated with 27 examples.

Synthesis of N,O-bidentate organic difluoroboron complexes and their photophysical studies.

We disclose a novel boron trifluoride induced C-H activation and difluoroboronation at room temperature, thus providing a straightforward gateway to a series of N,O-bidentate organic BF complexes. The scope of the method is demonstrated with 24 examples. All the synthesized compounds exhibit fluorescence and some of them have large Stokes shifts.

Three-Component Cycloaddition of Nitriles: Construction of Bicyclic 4-Aminopyrimidines and Their Photophysical Studies.

A base-induced synthesis of bicyclic 4-aminopyrimidines by the cycloaddition of three types of nitriles is reported. The scope of the method is demonstrated with 44 examples. Products are found to have luminescence properties and show potential applications as organic luminescent layer materials.

Copper(II)-Catalyzed Selective C-H Bond Formylation: Synthesis of Dialdehyde Aniline.

A simple and efficient method for the synthesis of dialdehyde aniline in good yields (up to 83%) is explored using Cu(OTf) as the catalyst, Selectfluor as the radical initiator, and DMSO as both the carbon and oxygen sources. Experimental studies indicate that the reaction is achieved by the formylation of two C-H bonds, first at the para-position and then at the ortho-position. A possible mechanism is proposed, including the thermal homolysis of Selectfluor, the Cu(II)-facilitated formylation of the C-H bonds, and the hydrolysis of the amide under alkaline conditions in air atmosphere.

Solvent-Free Strategy for Direct Access to Versatile Quaternary Ammonium Salts with Complete Atom Economy.

A solvent-free method for the synthesis of quaternary ammonium salts (QAS) by iodoquaternization of alkenes with N-heteroarenes was reported. Its advantages lie in energy-saving and clean production by using iodine as the oxidant and manual grinding the starting materials, together with the complete atom economy and low process mass intensity (PMI) value. Demonstrated by 50 examples, the generated QAS was proved to be able to produce valuable chemicals, such as biological protease inhibitors, anti-cancer agents, and organic fluorescent materials.

Iodine-Mediated Pyridine Ring Expansion for the Construction of Azepines.

A synthesis of azepines by the expansion of pyridine rings promoted by iodine in air is reported. The scope of the method is demonstrated with 27 examples. Two iodinations are involved in the reaction, in which the second iodination leads to the opening of the six-membered ring.

Synthesis of methylene-bridged α,β-unsaturated ketones: α-C-H methylenation of aromatic ketones using Selectfluor as a mild oxidant.

A three starting material four component reaction (3SM-4CR) is developed for the synthesis of α,β-unsaturated ketones and β-amino ketones in good yields. The reaction employs tetramethylethylenediamine (TMEDA) as a methylene and terminal olefin source, and Selectfluor as a mild oxidant. TMEDA worked as a dual synthon to provide two carbons in this metal-free transformation process.

A three-component iodine-catalyzed oxidative coupling reaction: a heterodifunctionalization of 3-methylindoles.

A metal-free method for the synthesis of heterodifunctional indole derivatives is developed through TBHP/KI-mediated oxidative coupling. The reaction constructs C-O and C-C bonds in succession with the help of tert-butyl peroxy radicals generated by the TBHP/KI catalytic system, enabling the direct realization of the heterodifunctionalization of indole in one pot. The product of this reaction is a novel heterodifunctional compound.

Selectfluor facilitated bridging of indoles to bis(indolyl)methanes using methyl -butyl ether as a new methylene precursor.

A novel, green and efficient method is developed for the synthesis of methylene bridged bis(indolyl)methanes in good to excellent yields. The reaction employs methyl tert-butyl ether (MTBE) as the methylene source and selectfluor as an oxidizing agent. The scope and versatility of the methods have been successfully demonstrated with 48 examples.

Copper(II)-Dioxygen Facilitated Activation of Nitromethane: Nitrogen Donors for the Synthesis of Substituted 2-Hydroxyimino-2-phenylacetonitriles and Phthalimides.

A simple and efficient method is explored for the synthesis of 2-hydroxyimino-2-phenylacetonitriles (2) and phthalimides (4), by using nitromethane as nitrogen donors. Both reactions are promoted by Cu(II) system with the participation of dioxygen as an oxidant. The scope of the method has been successfully demonstrated with a total of 51 examples.

Copper(II)-hydroxide facilitated C-C bond formation: the carboxamido pyridine system the methylimino pyridine system.

A copper(ii)-hydroxide-induced carbon-carbon bond formation reaction is explored with the synthesis of an asymmetric carboxamido-methylimino pyridine Cu(i) complex of [CuI(py(N-C[double bond, length as m-dash]O)(N[double bond, length as m-dash]C-C)ph2Me2)2]- (12). Two imine-methyl groups are coupled to form a bridged C-C bond (N[double bond, length as m-dash]C-C-C-C[double bond, length as m-dash]N) at the methyl positions with the reduction of two Cu2+ center ions to Cu+. The reaction is checked with three dicarboxamido pyridine [CuII-OH] complexes, with which dinuclear Cu(i) complexes of [Cu2(py(N-C[double bond, length as m-dash]O)2ph2R2)2]2- (R = methyl (3), methyl and allyl (6)) and trinuclear [CuII-CuI-CuII] complex of [Cu3(⊂20-py(N-C[double bond, length as m-dash]O)2ph2dienMe3)2]+ (9) are obtained.

Temperature controlled condensation of nitriles: efficient and convenient synthesis of β-enaminonitriles, 4-aminopyrimidines and 4-amidinopyrimidines in one system.

A series of β-enaminonitriles, 4-aminopyrimidines and 4-amidinopyrimidines were synthesized by condensation of organonitriles in one system. A wide variety of compounds were obtained in good to excellent yields by simply controlling the reaction temperature. The base-induced transformation process is easy for production.

Experimental and mechanistic insights into copper(ii)-dioxygen catalyzed oxidative N-dealkylation of N-(2-pyridylmethyl)phenylamine and its derivatives.

A di-(2-pyridylmethyl)phenylamine ((PyCH)NPh) supported Cu(ii)/O catalytic system was explored with the synthesis of pyridylmethyl-based compounds of carboxylate (PyCOOH), amide (PyC(O)NHPh), and imine (PyCH[double bond, length as m-dash]NPh) from the oxidative N-dealkylation of N-(2-pyridylmethyl)phenylamine (PyCHNHPh) and its derivatives, by means of controlling the addition of a base and/or water to the reaction system under a dioxygen atmosphere at room temperature. Experimental studies showed that the imine and amide species could be precursors in succession in the way to the final oxidation state of carboxylates. A cyclic catalytic mechanism was proposed including the base triggered C-H bond activation of the 2-pyridylmethyl group (PyCH-) and the intermolecular Cu-OOH α-hydrogen atom abstraction from the coordinated imine substrate (PyCH[double bond, length as m-dash]NPh).

High-pressure studies of palladium and platinum thioether macrocyclic dihalide complexes.

The mononuclear macrocyclic Pd(II) complex cis-[PdCl2([9]aneS3)] ([9]aneS3 = 1,4,7-trithiacyclo-nonane) converts at 44 kbar into an intensely coloured chain polymer exhibiting distorted octahedral coordination at the metal centre and an unprecedented [1233] conformation for the thioether ligand. The evolution of an intramolecular axial sulfur-metal interaction and an intermolecular equatorial sulfur-metal interaction is central to these changes. High-pressure crystallographic experiments have also been undertaken on the related complexes [PtCl2([9]aneS3)], [PdBr2([9]aneS3)], [PtBr2([9]aneS3)], [PdI2([9]aneS3)] and [PtI2([9]aneS3)] in order to establish the effects of changing the halide ligands and the metal centre on the behaviour of these complexes under pressure.

Synthesis of binucleating macrocycles and their nickel(II) hydroxo- and cyano-bridged complexes with divalent ions: anatomical variation of ligand features.

The planar NNN-pincer complexes [M(II)(pyN(2)(Me2))(OH)](1-) (M(II) = Ni, Cu) fix CO(2) in η(1)-OCO(2)H complexes; results for the copper system are described. Mn(II), Fe(II), Co(II), and Zn(II) behave differently, forming [M(II)(pyN(2)(Me2))(2)](2-) with N(4)O(2) coordination. Incorporation of the Ni(II) pincer into binucleating macrocycle 2 containing a triamino M(II) locus connected by two 1,3-biphenylene groups affords proximal Ni(II) and M(II) sites for investigation of the synthesis, structure, and reactivity of Ni-X-M bridge units.

Fast carbon dioxide fixation by 2,6-pyridinedicarboxamidato-nickel(II)-hydroxide complexes: influence of changes in reactive site environment on reaction rates.

The planar complexes [Ni(II)(pyN(2)(R2))(OH)](-), containing a terminal hydroxo group, are readily prepared from N,N'-(2,6-C(6)H(3)R(2))-2,6-pyridinedicarboxamidate(2-) tridentate pincer ligands (R(4)N)(OH), and Ni(OTf)(2). These complexes react cleanly and completely with carbon dioxide in DMF solution in a process of CO(2) fixation with formation of the bicarbonate product complexes [Ni(II)(pyN(2)(R2))(HCO(3))](-) having η(1)-OCO(2)H ligation. Fixation reactions follow second-order kinetics (rate = k(2)'[Ni(II)-OH][CO(2)]) with negative activation entropies (-17 to -28 eu).

Redox non-innocence of thioether crowns: spectroelectrochemistry and electronic structure of formal nickel(III) complexes of aza-thioether macrocycles.

The Ni(II) complexes [Ni([9]aneNS(2)-CH(3))(2)](2+) ([9]aneNS(2)-CH(3)=N-methyl-1-aza-4,7-dithiacyclononane), [Ni(bis[9]aneNS(2)-C(2)H(4))](2+) (bis[9]aneNS(2)-C(2)H(4)=1,2-bis-(1-aza-4,7-dithiacyclononylethane) and [Ni([9]aneS(3))(2)](2+) ([9]aneS(3)=1,4,7-trithiacyclononane) have been prepared and can be electrochemically and chemically oxidized to give the formal Ni(III) products, which have been characterized by X-ray crystallography, UV/Vis and multi-frequency EPR spectroscopy. The single-crystal X-ray structure of [Ni(III)([9]aneNS(2)-CH(3))(2)](ClO(4))(6)·(H(5)O(2))(3) reveals an octahedral co-ordination at the Ni centre, while the crystal structure of [Ni(III)(bis[9]aneNS(2)-C(2)H(4))](ClO(4))(6)·(H(3)O)(3)·3H(2)O exhibits a more distorted co-ordination. In the homoleptic analogue, [Ni(III)([9]aneS(3))(2)](ClO(4))(3), structurally characterized at 30 K, the Ni-S distances [2.

Kinetics and mechanistic analysis of an extremely rapid carbon dioxide fixation reaction.

Carbon dioxide may react with free or metal-bound hydroxide to afford products containing bicarbonate or carbonate, often captured as ligands bridging two or three metal sites. We report the kinetics and probable mechanism of an extremely rapid fixation reaction mediated by a planar nickel complex [Ni(II)(NNN)(OH)](1-) containing a tridentate 2,6-pyridinedicarboxamidate pincer ligand and a terminal hydroxide ligand. The minimal generalized reaction is M-OH + CO(2) → M-OCO(2)H; with variant M, previous rate constants are ≲10(3) M(-1) s(-1) in aqueous solution.

Reactions of the terminal Ni(II)-OH group in substitution and electrophilic reactions with carbon dioxide and other substrates: structural definition of binding modes in an intramolecular Ni(II)...Fe(II) bridged site.

A singular feature of the catalytic C-cluster of carbon monoxide dehydrogenase is a sulfide-bridged Ni...

Cleavage of Ni-(mu(2)-S)-Ni bridges in dinuclear nickel(II) dithiolate pincer complexes and related reactions.

Pyridine-2,6-dimethanethiolate and pyridine-2,6-dithiocarboxylate form sparingly soluble Ni(II) pincer complexes formulated as [Ni(pdmt)](2) and [Ni(pdtc)](2), respectively, with two Ni-(mu(2)-S)-Ni bridges. In acetonitrile reaction systems, the latter undergoes the facile bridge cleavage reactions [Ni(pdtc)](2) + 2L(0,-) --> 2[Ni(pdtc)L](0,-) with an extensive set of nucleophiles to afford planar mononuclear products with L(-) = halide, CN, Me(3)SiO(-), RS(-) and L(0) = Et(3)P and a N-heterocyclic carbene. [Ni(pdmt)](2) is considerably less reactive toward bridge disruption.

Crystallographic, electrochemical, and electronic structure studies of the mononuclear complexes of Au(I)/(II)/(III) with [9]aneS2O ([9]aneS2O = 1-oxa-4,7-dithiacyclononane).

The mononuclear macrocyclic complexes [Au(I)([9]aneS2O)2]BF4 x MeCN 1a, [Au(II)([9]aneS2O)2](BF4)2 x 2 MeCN 2a, and [Au(III)([9]aneS2O)2](ClO4)6(H5O2)(H3O)2 3 ([9]aneS2O = 1-oxa-4,7-dithiacyclononane) have been prepared and structurally characterized by single crystal X-ray crystallography. The oxidation of [Au([9]aneS2O)2](+) to [Au([9]aneS2O)2](2+) involves a significant reorganization of the co-ordination sphere from a distorted tetrahedral geometry in [Au([9]aneS2O)2](+) [Au-S 2.3363(12), 2.