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Colorless block crystals of [Ag14I16(HDABCO)2]·DABCO are synthesized from AgI dissolved in saturated KI solution and DABCO in EtOH (room temperature, 14 d, 51% yield).

Replacing the rare and precious platinum (Pt) electrocatalysts with earth-abundant materials for promoting the oxygen reduction reaction (ORR) at the cathode of fuel cells is of great interest in developing high-performance sustainable energy devices. However, the challenging issues associated with non-Pt materials are still their low intrinsic catalytic activity, limited active sites, and the poor mass transport properties. Recent advances in material sciences and nanotechnology enable rational design of new earth-abundant materials with optimized composition and fine nanostructure, providing new opportunities for enhancing ORR performance at the molecular level. This Review highlights recent breakthroughs in engineering nanocatalysts based on the earth-abundant materials for boosting ORR.

Nitrogen-functionalized carbon nanotubes are promising materials in catalysis due to their versatile surface properties involving nitrogen groups, oxygen groups, surface defects and metal impurities. These factors can be used to tune the dispersion, morphology, crystal structure, electronic structure, mobility/stability and finally the catalytic performance of supported metal nanoparticles. This review focuses on selected examples aiming at understanding the interactions between surface groups, defects, and metal species and their impact on the catalytic properties in electrocatalysis and gas-phase redox catalysis.

Under visible light irradiation of N-bromosuccinimide methyl 2-(azidomethyl)-3-aryl-propenoates and -acrylonitriles convert to the corresponding iminyl radicals which undergo intramolecular ortho attack on the aryl ring, affording methyl quinoline-3-carboxylates and 3-carbonitriles, respectively.

An efficient method for the one-pot synthesis of 2-oxazolines from ethyl α-cyanocinnamate derivatives with N-bromoacetamide in the presence of K3PO4 has been developed. The reaction performed smoothly and cleanly to give 2-oxazolines in good to excellent yields (up to 98%) within 4.5 h in acetone at room temperature without protection of inert gases. A total of 13 examples have been investigated. A possible nucleophilic addition reaction mechanism is proposed.

A synthesis of quinoxalin-2-ones or heterocyclic spiro compounds is developed using NBS-promoted reactions of 2-azido-N-phenylacetamides under visible light irradiation.

A one-pot synthesis of indolo[2,3-c]quinolin-6(7H)-ones was achieved by sequential photocyclizations of 3-(2-azidophenyl)-N-phenylacrylamides in moderate to high yields. The reactions proceeded via photochemical cyclization of aryl azides to form N-phenylindol-2-carbamides and subsequent 6π-electrocyclic reaction and oxidative aromatization to afford the corresponding indolo[2,3-c]quinolin-6(7H)-ones.

A one-pot synthesis of benzoyl-substituted fused pyrroles or indoles in moderate to high yields has been achieved by the photocyclization/photohydrolysis reactions of N-(ω-phenylalkynyl)-2-chloropyrrole-3-carbaldehydes or 3-acyl-N-(ω-phenylbutynyl)-2-haloindoles in wet acetone. The formation of all these products could be inferred by a two-step reactions, namely, photoinduced chlorine atom-transfer cyclization and subsequent photohydrolysis.

An efficient procedure for the synthesis of fused benzo[c]carbazoles has been achieved in moderate to high yields by the one-pot photochemical annulation of 3-acyl-2-haloindoles with tethered styrenes by photoinduced electron-transfer coupling, electrocyclic reactions, and deacylative aromatization in the presence of pyridine. Fused furo[2,3-c]carbazoles were also synthesized under the same conditions. 5,6-Dihydrobenzo[c]pyrrolo[1,2,3-lm]carbazoles were oxidized by DDQ to afford aromatic benzo[c]pyrrolo[1,2,3-lm]carbazole products in moderate to high yields.

The cyclization of azides (I) and (III) proceeds via nitrene electrophilic addition and rearrangement reactions to give fused indole derivatives under both photochemical and thermal conditions.

Iodine was added to 3-(trimethylsilyl )allylic phosphonium ylide regiospecifically to give 3-iodo-3-trimethylsilyl allylic phosphonium ylide, which reacted with carbonyl compounds to give 1-iodo-1-trimethylsilyl 1,3-dienes with high stereoselectivity in good yield.

A one-pot reaction of 3-trimethylsilylprop-2-enyl(diisobutyl)telluronium bromide 1 with α,β-unsaturated ketones gives, by way of Michael addition in the presence of caesium carbonate under solid–liquid phase-transfer conditions, trimethylsilylvinylcyclopropanes both in high to excellent yields and with high stereoselectivity. A similar high-yielding cyclopropanation occurs in THF/trace of water with diisobutyl telluride as catalyst in a one-pot reaction of (E)-3-bromo-1-trimethylsilylprop-1-ene with α,β-unsaturated ketones in the presence of caesium carbonate.

A monolayer of a C60 mixture with arachidic acid (1:1) and C60-pyrrolidine derivatives [C60(C3H6NR); R = H (1), C6H5 (2), o-C6H4NO2 (3), and o-C6H4NMe2 (4)] were successfully obtained at the air/water interface and deposited onto solid substrates with transfer ratios of about 0.90 ± 0.05 at 30 mN·m-1 by the Langmuir−Blodgett (LB) technique. The photoelectrochemical investigation of these compounds on SnO2 electrodes was carried out. The photocurrent was determined under nitrogen atmosphere because oxygen can suppress the photocurrents. Results showed that electrons flow from the electrolyte through LB film to SnO2 and a chemical energy conversion occurs together with the photoelectric conversion. Positive bias voltage, electron donor, the incident light intensity, and the electron-repulsion groups in the derivatives are beneficial factors for generating higher photocurrent. The quantum yields vary from 0.015 to 0.069 for C60 and its derivatives 1−4.

A series of planar chiral 1,1′-P,N-2′-substituted ferrocene ligands 9–12 and 16, prepared with diastereopurity >99∶1, have been used to examine the role of planar chirality, and significant effects on enantioselectivity as well as the control of absolute configuration in palladium-catalyzed allylic alkylation as a model reaction were observed.

The Pd(0)-catalyzed coupling reaction of electron-deficient alkenyl halides with the organozinc formed by the subsequent treatment of 1-phenylalk-1-yne with n-BuLi and ZnBr2 with or without a catalytic amount of HgCl2 was studied. Both the allene-formation- and the alkyne-formation-type coupling reactions were observed with high regio- and stereoselectivity: the reaction of 1-phenylprop-1-yne afforded 6-phenylhex-5-yn-2(or 3)-enoates and -enitriles, while the reaction of 1-phenylhex-1-yne formed 4-phenyl-6-substituted-hexa-2,4,5-trienoates. A plausible explanation for the regioselectivity was discussed. The double bonds in 6-phenylhex-5-yn-2-enoates were prone to migrate to the position conjugated with the carbon−carbon triple bonds to form 6-phenylhex-5-yn-3-enoates at higher temperature. The migration did not occur in absence of an excess amount of allenic/propargylic zinc reagent or at low temperature.

A series of novel planar chiral 2‘-substituted 1,1‘-P,N-ferrocene ligands 9−11, 14, and 16 were prepared with diastereopurity >99:1 and found to be effective in asymmetric allylic alkylation and amination reactions. Ligand 14 furnished the highest enantiomeric excess, 98.5% and 96.5% ee in alkylation and amination reactions, respectively. The role of planar chirality in asymmetric reactions has been examined, and decisive effects on enantioselectivity as well as the control of absolute configuration in palladium-catalyzed allylic alkylation and amination reactions were observed. To clarify why and how the planar chirality governed the stereochemical outcome, X-ray crystallographic structures of η3-diphenylallyl Pd complexes, 1H NMR, 31P NMR spectra of palladium dichloride complexes, and η3-diphenylallyl Pd complexes of three 1,1‘-P,N-ferrocene ligands were analyzed with the aid of COSY and 2D NOESY experiments. All results led to the conclusion that planar chirality influences the stereochemical outcome b...

Soluble PEG-supported telluride 2 was synthesized and found to be an effective catalyst for the catalytic Wittig-type reaction to give a variety of α,β-unsaturated esters in high yields with excellent E-stereoselectivity in the presence of sodium bisulfite as well as triphenyl phosphite.

Palladium-catalyzed asymmetric allylic substitutions using thioether and phosphino derivatives of ferrocenyloxazoline as ligands have been investigated with a focus on studying the role of planar chirality. In allylic alkylation, up to 98% ee and 95% ee were achieved with S,N- and P,N-ligands, respectively. In allylic amination, 97% ee was realized with P,N-ligands in the presence of TBAF. Several palladium allylic complexes were characterized by X-ray diffraction and/or solution NMR. Thioether derivatives of ferrocenyloxazolines with only planar chirality showed lower enantioselectivity in the allylic alkylation except 5c because of the formation of a new chirality on sulfur atom during the coordination of sulfur with palladium. On the other hand, in the planar chiral P,N-ligands without central chirality, (Sp)-11a-c there was no such disturbance and comparatively higher enantioselectivity in both palladium-catalyzed allylic alkylation and amination was provided.

Soluble poly(ethylene glycol) (PEG)-supported telluride 2 was designed and synthesized for catalytic Wittig-type reactions. It was found that the catalytic loading could be reduced from 20 to 2 mol % by the introduction of PEG (even to 0.5 mol % when some telluride salts were used as the catalyst). Under the catalytic reaction conditions, a wide variety of aldehydes with different structures could react with bromoacetate to afford β-substitutited or α,β-disubstituted unsaturated esters in high yields with excellent E-stereoselectivity. The modified process, by using sodium bisulfite instead of triphenyl phosphite, represented a very simple product isolation procedure. The roles of PEG for promoting the ylide formation and stabilizing the catalytic species were disclosed. The mechanism was also studied.

A rapid and efficient method for the synthesis of substituted 1,3,4-thiadiazoles is described. The products have been characterized by analytical and spectral (IR and H'NMR) data.