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The use of small molecules with defined cavities that catalyze unique chemical transformations to emulate enzyme sites have resulted in sustainable catalytic transformation with unprecedented selectivity that proceed under ambient conditions using benign solvents and clean energy. Of these reported host molecules, Werner-type capsules have been of particular interest to researchers because of their structural modifiability and rich chemical properties arising from their uniform cavities. In this review, we focus on the catalytic properties of several important catalytic transformations that have occurred within the confined pockets of these Werner-type capsules with special attention to the aspects that are derived from the ‘confined space effect’ of these Werner-type capsules.

MoVOx-type catalysts are very active and very selective in the commercially important oxidation of acrolein to acrylic acid. To contribute to unravelling the thus far poorly understood mechanism, we carried out hybrid DFT calculations on embedded cluster models, focusing on the so-called pentameric unit as active site. In the absence of water, we calculated a large energy span, 169 kJ mol–1, for this transformation. After addressing the hydrolysis of the surface, we examined four scenarios of the acrolein conversion to explore the effect of water. The most favorable variant has a notably lower energy span, 146 kJ mol–1, in line with experimental observations that indicate a strong acceleration of the catalytic transformation in the presence of water.

Amides are generally considered as a low-reactive chemical entity among the carbonyl group, and therefore fewer opportunities to be involved in catalytic transformations as substrates. The origin of the stable nature of amides is resonance stabilization in the planar structure, which has drawn considerable attention from organic and physical chemists, leading to the discovery of distorted amides that exhibit a substantially reactive nature. Recent focus in this field is on the catalytic transformation of designed amides with moderate distortion or reduced resonance stabilization. This digest reviews the brief history of the quest for highly distorted amides and introduces a collection of recent studies on catalytic transformations of designed amides.

The oxidation of sp 3 C H bonds in N- alkylhydrazides was achieved en route to the efficient synthesis of a broad series of 1,3,4-oxadiazoles. Mechanistic studies have revealed that N- acylhydrazone is a key intermediate in this catalytic transformation.

The high-quality bio-jet fuel derived from biomass resources can directly replace commercial fossil fuels for aviation due to the similar composition and properties. However, conventional technologies on hydrodeoxygenation of plant oil can’t produce renewable aromatics, which is the key component in the jet fuel. In this paper, the bio-jet fuels were produced by aqueous-phase processing of plant sugar/polyol. Liquid fuel yield of 31.8% with sorbitol conversion of 98% was obtained under the conditions of 280 °C, WHSV of 1.25 h −1 , GHSV of 2500 h −1 and 4.0 MPa hydrogen pressure. The content of aromatics and napthenes was above 72 wt.% in the produced liquid fuels. This process uses a wide variety of both cellulosic and conventional plant sugars, providing an economic route to sustainable bio-based jet fuel production, which includes normal and iso-paraffins, naphthenes, and aromatics required for aviation.

Biomass resources have been considered as one of the most promising renewable feedstocks to replace fossil resources. However, valorization of biomass is still challenging due to concerns about environmental sustainability and low efficiency of conversion processes. Mechanical ball milling technology, which has emerged as an efficient and environmentally sound alternative to traditional method, can overcome this obstacle to facilitate biomass valorization. Mechanical energy in the ball milling process can induce chemical reactions of biomass in solvent-less/-free conditions. This work reviews the latest advances in the mechanochemical conversion of biomass into chemicals and carbon materials. The initial pretreatment of biomass, catalytic transformation process of biomass, and synthesis of biomass-derived carbon materials (ordered mesoporous carbons, hierarchically porous carbons, carbon/metal composites, etc.) are discussed in detail. Mechanisms, development history, key influencing factors, and technology readiness level of ball milling on biomass valorization are also elucidated. Limitations and opportunities associated with this green technology are highlighted for future research directions.

The direct catalytic thermo-catalytic transformation of wood in presence of molecular hydrogen has been demonstrated. The resulting organic liquid consists of saturated alkanes and aromatics and was obtained with a yield up to 30 wt.%. Importantly, the oxygen content is about 3 wt.% (

Phosphine-free ruthenium alkylidene complexes, [RuCl 2 (=CH- o -O i PrC 6 H 4 )(IMesH 2 )], [Ru(CF 3 CO 2 ) 2 (=CH- o -O i PrC 6 H 4 )(IMesH 2 )], and [RuCl 2 (=CHPh)(3-Br-py) 2 (IMesH 2 )], were found as catalyst precursors for non-metathesis transformations of phenylacetylene, e.g. cyclotrimerization and dimerization. Selective product formation was affected by modulating the coordination sphere of the catalyst and temperature. An NMR study under various experimental conditions and DFT calculations taken together permitted the conclusion that the degradation of the alkylidene complex took place in the initial step, regardless of the manner of alkyne addition.

A novel organocatalytic highly enantioselective nitrocyclopropanation reaction of α,β-unsaturated aldehydes is presented. The 1-nitro-2-formylcyclopropane derivatives synthesized from this catalytic transformation were converted to the corresponding β-nitromethyl-acid esters, which are excellent precursors of GABA analogues such as Baclofen, by subsequent organocatalytic chemoselective ring-opening.

The synthesis and characterization of several new bicyclophosphites via reactions of (i) ethyl 1-thio-α- d -glucofuranoside 3,5,6-phosphite with acid chlorides (phthalic or butylphosphoric), (ii) ethyl 1-thio-α- d -glucofuranoside 3,5,6-phosphite with 2-chloro-5,5-dimethyl-1,3,2-dioxaphosphorinane and (iii) the tetraol system of ethyl 1-thio-α- d -glucofuranoside and hexaethyltriamidophosphite are reported. Unusual catalytic transformation of P(III)-compounds into the respective P(V)-spieces under extraordinary mild conditions by reaction with sulfur and selenium in the presence of triethylamine was discovered for the first time.

Various alkyl and aryl mono- and disubstituted 3,6-dihydro-1,2-dithiins have been synthesised from their corresponding vinylthiiranes exploiting Adams' tungsten pentacarbonyl monoacetonitrile catalytic transformation. New conclusions pertaining to the rate determining step, the sensitivity of the process to precursor sterics and electronics, and the nature of various reaction intermediates are highlighted.

A review of the large number of studies completed during the current decade on the chemistry of ruthenium and osmium vinylidene complexes is presented. Interest in these studies arises not only from the reactivity modes and structural properties, but also because vinylidene species play an important role in the selective catalytic transformation of terminal alkynes (polymerization, CC bond formation in the condensation of alkynes with other substrates, etc.). Attention is mainly focused on the mononuclear compounds, studying their preparative methods where coordinatively unsaturated species and good donor ligands are often involved. Recent methods of synthesis from polyhydrides are also summarized. Metal alkynyl derivatives are closely related to vinylidene complexes, both being common precursors to, and reaction products of vinylidene complexes. Subsequently, 1-alkyne and π-alkyne to vinylidene rearrangements on these metal centers are studied. The transformations from vinyl 14 electron to hydride-vinylidene 16 electron species and from hydride–vinylidene to ethylidyne species, etc. are also considered.

Direct functionalization of aromatic substituents on [28]hexaphyrin was achieved by Ir-catalyzed borylation with the Smith–Miyaura–Hartwig protocol. High para selectivity was observed in the reaction on 2,6-dichlorophenyl and 2,6-dimethoxyphenyl substituents of [28]hexaphyrin. The reaction with [26]hexaphyrin resulted only in reduction of the substrate to provide [28]hexaphyrin without borylation, thus highlighting the importance of the oxidation state of substrates in this catalytic transformation. The borylated hexaphyrin can be used for Suzuki–Miyaura cross-coupling reaction.

The reaction of the chiral tripod ligands X 2 POCH(CH 2 P(Ph) 2 )(CH 2 PR 2 ) ((±)- and R - 1a,b : X 2 = 2,2′-biphenoxy-; PR 2 = P(4-Me-C 6 H 4 ) 2 ( 1a ), PR 2 = dibenzophospholyl(DBP)- ( 1b )) and MeC(CH 2 P(Ph) 2 )(CH 2 PR′ 2 )(CH 2 PR″ 2 ) ((±)- and R - 2 : PR′ 2 = P(3,5-Me 2 -C 6 H 3 ) 2 ; PR″ 2 = DBP) with [Rh I (COD)Cl] 2 is investigated. It yields tripod rhodium COD complexes [( 1a,b )Rh I (COD)]PF 6 ((±)- and R - 3a,b ) and [( 2 )Rh I (COD)]PF 6 ((±)- and R - 4 ). The tripod ligand is coordinated by all three donor groups in each case, irrespective of the different donor capabilities of the coordinating groups. The complexes 3a,b and 4 are catalysts for the hydrogenation of the prochiral olefins acetamidocinnamic acid and dimethylitaconate. Both the poor activity and the low enantioselectivity compared to rhodium complexes containing chiral bisphosphino ligands can be explained by the presence of a third coordinating donor group in the ligand. Thus the trihapto coordination of the tripodal ligands is shown to be more of an impediment for this type of catalytic transformation.

A variety of neutral arene-ruthenium-carbenes of type (arene)RuCl 2 (= C(NR)CH 2 CH 2 N R) have been used for the catalytic transformation of ( Z )-3-methylpent-2-en-4-yn-1-ol into 2,3-dimethylfuran. The catalytic reaction takes place at 80°C with mononuclear complexes III–V to afford the furan in ∼ 90% yield. The binuclear catalysts VIa and VIIa having a linked bis-carbene bridge operate at room temperature to initiate an exothermic reaction offering 90–97% of furan.

The catalytic transformation from hBN to cBN in the system Mg 3 N 2 -BN was investigated in more detail under high pressures and temperature using in-situ sensing methods. At the threshold of the cBN formation region (approximately 1550 K at 5.5 GPa), very fast formation processes leading to submicron cBN grains are observed in a small temperature interval (140 K at 5.5 GPa). The transformation proceeds in a eutectic melt. Model assumptions of dissolution and precipitation could be confirmed. The only intermediate phase formed under these thermodynamic conditions is Mg 3 BN 3 thus forming the solvent for this process.

The unusual results of the present authors' research work obtained for the last 3 years in the field of synthesis and transformation of organomagnesium compounds with metal complex catalysts are considered in this review. Special attention has been paid to catalytic cyclometallation of linear and cyclic olefins with n-RZMg, synthesis of alkenyl organomagnesium compounds from a-olefins and RZMg, and catalytic transformation of cyclopentanes in the presence of Cp 2 ZrCl 2 . The reaction mechanism implying the formation of zircona-cyclopentane complexes as intermediate species are discussed.

This report reviews our recent studies of the catalytic transformations of thiiranes and vinylthiiranes by tungsten pentacarbonyl complexes. Whereas the thiranes yield only macrocyclic polydisulfides, the latter reactions yield only the cyclic monodisulfides known as 3,6-dihydro-1,2-dithiins.

Nitrosobenzene is converted into azoxybenzene in alcoholic media in the presence of Ru(CO)3(PPh3)2 as catalyst and under an inert atmosphere; Fe(CO)3(PPh3)2 and palladium complexes such as PdL2Cl2 (L  PhNO, p-MeC6H4NH2, PPh3) and Pd3(CO)3(PPh3)4, are less active as catalysts. Under CO pressure and with Ru(CO)3(PPh3)2 as catalyst, nitrosobenzene is converted into azobenzene and aniline, while azoxybenzene gives azobenzene.

The kinetics of the catalytic transformation of cumyl and tert. -butyl hydro-peroxides under gas chromatographic column conditions has been studied. Amphoteric and acidic metal oxides were used as the catalysts. The rate constants of the reactions and half-lives of the hydroperoxides studied have been calculated. The catalysts used can be arranged in order of decreasing catalytic activity: V 2 O 5 > Co 2 O 3 > Fe 2 O 3 > Al 2 O 3 , ZnO. The kinetic curves for the hydroperoxide consumption and the accumulation of the main products of their catalytic decomposition have been obtained.

To elucidate the possible natural evolutionary pathways for the transformation of pentacyclic triterpenoids, three terpenoid samples, Δ 2 -allobetulene, tetranormethylallobetulheptaene and fernenes were heated independently at 150°C for 7 weeks with montmorillonite clay. Common products from these reactions consisted of di, tri-, tetra-, and pentacyclic hydroaromatic and aromatic hydrocarbons, which are commonly found in higher rank coals. C-ring cleaved (8,14-seco) aromatic terpenoid derivatives were also found in the thermal catalytic reaction products of Δ 2 -allobetulene. Such compounds could be important intermediates in the formation of bicyclic hydrocarbons from pentacyclic triterpenoids.

From an investigation of the autoxidation of diethylcadmium (DEC) in n-heptane the formation of a reversible 1 2 DEC-oxygen complex has been established by a kinetic method. Some properties of this complex have been studied, viz. its ability to undergo spontaneous and catalytic transformation into bis(ethylperoxy)cadmium and its ultraviolet and infrared absorption spectra.