Valentine P. Ananikov

Toxicity of Ionic Liquids: Eco(cyto)activity as Complicated, but Unavoidable Parameter for Task‐Specific Optimization

Rapid progress in the field of ionic liquids in recent decades led to the development of many outstanding energy-conversion processes, catalytic systems, synthetic procedures, and important practical applications. Task-specific optimization emerged as a sharpening stone for the fine-tuning of structure of ionic liquids, which resulted in unprecedented efficiency at the molecular level. Ionic-liquid systems showed promising opportunities in the development of green and sustainable technologies; however, the chemical nature of ionic liquids is not intrinsically green. Many ionic liquids were found to be toxic or even highly toxic towards cells and living organisms. In this Review, we show that biological activity and cytotoxicity of ionic liquids dramatically depend on the nature of a biological system. An ionic liquid may be not toxic for particular cells or organisms, but may demonstrate high toxicity towards another target present in the environment. Thus, a careful selection of biological activity data is a must for the correct assessment of chemical technologies involving ionic liquids. In addition to the direct biological activity (immediate response), several indirect effects and aftereffects are of primary importance. The following principal factors were revealed to modulate toxicity of ionic liquids: i) length of an alkyl chain in the cation; ii) degree of functionalization in the side chain of the cation; iii) anion nature; iv) cation nature; and v) mutual influence of anion and cation.

Miniaturization of NMR Systems: Desktop Spectrometers, Microcoil Spectroscopy, and “NMR on a Chip” for Chemistry, Biochemistry, and Industry

Spectroscopy, and “NMR on a Chip” for Chemistry, Biochemistry, and Industry Sergey S. Zalesskiy,† Ernesto Danieli,‡ Bernhard Blümich,*,‡ and Valentine P. Ananikov*,†,§ †Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, 119991, Russia ‡Institut für Technische Chemie und Makromolekulare Chemie, RWTH Aachen University, Worringerweg 1, D-52074 Aachen, Germany Department of Chemistry, Saint Petersburg State University, Stary Petergof, 198504, Russia

Catalytic C–C and C–Heteroatom Bond Formation Reactions: In Situ Generated or Preformed Catalysts? Complicated Mechanistic Picture Behind Well-Known Experimental Procedures

In situ generated catalysts and preformed catalysts are two practical strategies widely used in cross-coupling methodology that have long been considered to involve the same active species in the catalytic cycle. Recent mechanistic studies have revealed two fundamentally different pictures of catalytic reactions in solution. Preformed catalysts with strongly bound ligands initiate transformations mainly involving single type of metal species. In contrast, in situ generated catalysts give rise to cocktail-type systems with different metal species presented in solution. The role of catalyst precursor, interconversions of catalytic species during reaction, stability and recycling of catalyst, catalysis by autocatalyst exhaust and plausible sources of metal-containing contaminants are the key points discussed in this review.

Catalytic Adaptive Recognition of Thiol (SH) and Selenol (SeH) Groups Toward Synthesis of Functionalized Vinyl Monomers

An unprecedented sustainable procedure was developed to produce functionalized vinyl monomers H(2)C═C(R)(FG) starting from a mixture of sulfur and selenium compounds as a functional group donor (FG = S or Se). The reaction serves as a model for efficient utilization of natural resources of sulfur feedstock in oil and technological sources of sulfur/selenium. The catalytic system is reported with amazing ability to recognize SH/SeH groups in the mixture and selectively incorporate them into valuable organic products via wastes-free atom-economic reaction with alkynes (HC≡CR). Formation of catalyst active site and the mechanism of the catalytic reaction were revealed by joint experimental and theoretical study. The difference in reactivity of μ(1)- and μ(2)-type chalcogen atoms attached to the metal was established and was shown to play the key role in the action of palladium catalyst. An approach to solve a challenging problem of dynamically changed reaction mixture was demonstrated using adaptive tuning of the catalyst. The origins of the adaptive tuning effect were investigated at molecular level and were found to be governed by the nature of metal-chalcogen bond.

Characterization of Molecular Systems and Monitoring of Chemical Reactions in Ionic Liquids by Nuclear Magnetic Resonance Spectroscopy

2.1. Structure and Dynamics of Neat Ionic Liquids 419 2.2. Water and Impurities Effects on Ionic Liquids 424 2.3. Water/Proton Removal 425 2.4. Solubility of Gases 426 2.5. Extraction and Separation 427 2.6. Solvent-Solute Interactions 428 2.7. Monitoring of Chemical Reactions 432 2.8. Transition Metal Complexes 436 2.9. Ionic Liquids Stability and Recycling 438 3. Overview of NMR Experiments in Ionic Liquids 439 3.1. 1H and 2H NMR Spectra 439 3.2. Heteronuclear Spectra 440 3.3. Diffusion Studies 441 3.4. Relaxation Measurements 442 3.5. Nuclear Overhauser Effect Measurements 442 3.6. Two-Dimensional NMR Spectroscopy 442 4. Practical Aspects of NMR Spectroscopy in Ionic Liquids 443

Mechanistic study of palladium catalyzed S–S and Se–Se bonds addition to alkynes

The mechanistic study of palladium catalyzed S � /S and Se � /Se bonds addition to alkynes revealed the involvement of dinuclear transition metal complexes in the catalytic cycle. Coordination of alkyne to dinuclear transition metal complex was found to be the rate determining step of the reaction. An unusual phosphine ligand effect increasing the yield of addition reaction was found in the studied system. A new synthetic procedure was developed to perform the catalytic reaction using easily available Pd(II) complex. The scope of the reaction and the reactivity of S � /S and Se � /Se bonds toward alkynes were investigated. The X-ray structure of the product of S � /S bond addition reaction showed favorable geometry for the possible application as a chelate ligand. # 2003 Elsevier B.V. All rights reserved.

Addition reactions of E-E and E-H bonds to triple bond of alkynes catalyzed by Pd, Pt, and Ni complexes (E=S, Se)*

The synthetic application and mechanistic aspects of transition-metal (Ni, Pd, Pt) catalyzed addition of E-E and E-H (E=S, Se) bonds to alkynes were investigated in detail. This study revealed major factors controlling the selectivity of such addition reactions. A new Ni-based catalytic system with a self-organized nanostructured catalyst has been designed to perform chemical transformation in high yield, under mild conditions.

Remarkable Ligand Effect in Ni- and Pd-Catalyzed Bisthiolation and Bisselenation of Terminal Alkynes: Solving the Problem of Stereoselective Dialkyldichalcogenide Addition to the CC Bond

We have developed two new catalytic systems based on Ni and Pd complexes to solve the challenging problem of dialkyldichalcogenide (Alk2E2; E=S, Se) addition to alkynes. A comparative study of two catalytic systems-Ni/PMe2Ph and Pd/PCy2Ph-has revealed that the Ni catalyst is superior with respect to high catalytic activity and more general scope relative to the Pd system. A novel synthetic methodology was developed for the preparation of (Z)-bis(alkylthio)alkenes and (Z)-bis(alkylseleno)alkenes from terminal alkynes with excellent stereoselectivity and high yields.

The First Molecular Level Monitoring of Carbohydrate Conversion to 5‐Hydroxymethylfurfural in Ionic Liquids. B2O3—An Efficient Dual‐Function Metal‐Free Promoter for Environmentally Benign Applications

The mechanistic nature of the conversion of carbohydrates to the sustainable platform chemical 5-hydroxymethylfurfural (5-HMF) was revealed at the molecular level. A detailed study of the key sugar units involved in the biomass conversion process has shown that the simple dissolution of fructose in the ionic liquid 1-butyl-3-methylimidazolium chloride significantly changes the anomeric composition and favors the formation of the open fructoketose form. A special NMR approach was developed for the determination of molecular structures and monitoring of chemical reactions directly in ionic liquids. The transformation of glucose to 5-HMF has been followed in situ through the detection of intermediate species. A new environmentally benign, easily available, metal-free promoter with a dual functionality (B(2)O(3)) was developed for carbohydrate conversion to 5-HMF.

General and Selective Head-to-Head Dimerization of Terminal Alkynes Proceeding via Hydropalladation Pathway

A general highly regio- and stereoselective palladium-catalyzed head-to-head dimerization reaction of terminal acetylenes is presented. This methodology allows for the efficient synthesis of a variety of 1,4-enynes as single E stereoisomers. Computational studies reveal that this dimerization reaction proceeds via the hydropalladation pathway.