Novruz G. Akhmedov

Triazole-Au(I) complexes: a new class of catalysts with improved thermal stability and reactivity for intermolecular alkyne hydroamination.

A series of 1,2,3-triazole-bound cationic Au(I) catalysts have been synthesized, and their structures have been characterized by X-ray crystallography. Variable-temperature NMR studies revealed dynamic triazole-Au cation coordination in solution. Reaction profiles clearly indicated that these new catalysts possess much better thermal stability than literature-reported Au catalysts, including IPrAu x NTf(2). By application of these catalysts, challenging intermolecular hydroaminations were achieved with less-reactive internal alkynes and unprotected aliphatic amines, giving excellent yields with low catalyst loading.

Gold-catalyzed oxidative cross-coupling of terminal alkynes: selective synthesis of unsymmetrical 1,3-diynes.

Gold-catalyzed oxidative cross-coupling of alkynes to unsymmetrical diynes has been achieved for the first time. A N,N-ligand (1,10-Phen) and PhI(OAc)2 were identified as crucial factors to promote this transformation, giving the desired cross-coupled conjugated diynes in excellent heteroselectivity (>10:1), in good to excellent yields, and with large substrate tolerability.

Gold‐Catalyzed Intermolecular CS Bond Formation: Efficient Synthesis of α‐Substituted Vinyl Sulfones

A general method for the synthesis of α-substituted vinyl sulfones makes use of a combination of a triazole gold complex and gallium triflate. This efficient CS bond formation between simple terminal alkynes and sulfinic acids provides access to various α-substituted vinyl sulfones.

Synthesis and bioassay of improved mosquito repellents predicted from chemical structure

Mosquito repellency data on acylpiperidines derived from the U.S. Department of Agriculture archives were modeled by using molecular descriptors calculated by CODESSA PRO software. An artificial neural network model was developed for the correlation of these archival results and used to predict the repellent activity of novel compounds of similar structures. A series of 34 promising N-acylpiperidine mosquito repellent candidates (4a–4q′) were synthesized by reactions of acylbenzotriazoles 2a–2p with piperidines 3a–3f. Compounds (4a–4q′) were screened as topically applied mosquito repellents by measuring the duration of repellency after application to cloth patches worn on the arms of human volunteers. Some compounds that were evaluated repelled mosquitoes as much as three times longer than N,N-diethyl-m-toluamide (DEET), the most widely used repellent throughout the world. The newly measured durations of repellency were used to obtain a superior correlation equation relating mosquito repellency to molecular structure.

1,2,3-Triazole as a Special “X-Factor” in Promoting Hashmi Phenol Synthesis

(31)P NMR experiments revealed rapid decomposition of the Ph(3)PAu(+)TfO(-) complex in the presence of the furan-yne, which resulted in poor reactivity as reported in the literature. Therefore, instead of tuning different ligands (PR(3)), the 1,2,3-triazole was applied as a special X-factor to stabilize the catalyst. The desired phenol products were prepared in excellent yields (1% cat. up to 95% yield) and chemoselectivity (>20:1).

Enantioselective Intermolecular Crossed‐Conjugate Additions between Nitroalkenes and α,β‐Enals through a Dual Activation Strategy

Double the fun: The title reaction was developed by using a Lewis base/iminium activation strategy (see scheme). The reaction proceeded with excellent yields and ee values, and the products were additionally transformed into a single enantiomer of a substituted pyrrolidine with excellent retention of configuration.

Amino acid-functionalized ionic liquid solid sorbents for post-combustion carbon capture.

Amino acid ionic liquids (AAILs) are potential green substitutes of aqueous amine solutions for carbon dioxide (CO2) capture. However, the viscous nature of AAILs greatly hinders their further development in CO2 capture applications. In this contribution, 1-ethyl-3-methylimidazolium lysine ([EMIM][Lys]) was synthesized and immobilized into a porous poly(methyl methacrylate) (PMMA) microsphere support for post-combustion CO2 capture. The [EMIM][Lys] exhibited good thermal stability and could be facilely immobilized into porous microspheres. Significantly, the [EMIM][Lys]-PMMA sorbents retained their porous structure after [EMIM][Lys] loading and exhibited fast kinetics. When exposed to CO2 at 40 °C, [EMIM][Lys]-PMMA sorbent exhibited the highest CO2 capacity compared to other counterparts studied and achieved a capacity of 0.87 mol/(mol AAIL) or 1.67 mmol/(g sorbent). The capture process may be characterized by two stages: CO2 adsorption on the surface of sorbent and CO2 diffusion into sorbent for further adsorption. The calculated activation energies of the two-stage CO2 sorption were 4.1 and 4.3 kJ/mol, respectively, indicating that, overall, the CO2 can easily adsorb onto this sorbent. Furthermore, multiple cycle tests indicated that the developed sorbents had good long-term stability. The developed sorbent may be a promising candidate for post-combustion CO2 capture.

Ligand-Assisted Gold-Catalyzed Cross-Coupling with Aryldiazonium Salts: Redox Gold Catalysis without an External Oxidant†

Gold-catalyzed C(sp)-C(sp(2)) and C(sp(2))-C(sp(2)) cross-coupling reactions are accomplished with aryldiazonium salts as the coupling partner. With the assistance of bpy ligand, gold(I) species were oxidized to gold(III) by diazonium without any external oxidants. Monitoring the reaction with NMR and ESI-MS provided strong evidence for the nitrogen extrusion followed by Au(III) reductive elimination as the key step.

Synergistic Gold and Iron Dual Catalysis: Preferred Radical Addition toward Vinyl-Gold Intermediate over Alkene.

A dual catalytic approach enlisting gold and iron synergy is described. This method offers readily access to substituted heterocycle aldehydes via oxygen radical addition to vinyl-gold intermediates under Fe catalyst assistance. This system shows good functional group compatibility for the generation of substituted oxazole, indole, and benzofuran aldehydes. Mechanistic evidence greatly supports selective radical addition to an activated vinyl-Au double bond over alkene. This unique discovery offers a new avenue with great potential to further extend the synthetic power and versatility of gold catalysis.

Immobilization of amino acid ionic liquids into nanoporous microspheres as robust sorbents for CO2 capture

Supported nanoporous microspheres immobilized with amino acid ionic liquids (AAILs) as robust sorbents were developed for CO2 capture. AAILs could be facilely immobilized into porous support materials. The developed sorbents exhibited fast kinetics as well as good sorption capacity, and can be regenerated and reused. The presented strategy may pave the way for developing AAIL-functionalized sorbents with high capacity and fast CO2 transport kinetics.