Luigi Mandolini

• Sapienza University of Rome

Second-order rate constants of aminolysis of 2-cyano-2-phenylpropanoic anhydride 3 by a series of N methylanilines differently substituted in the aromatic moiety (4a-d), were measured in dichloromethane. The common reaction product of aminolyses is 2 cyano 2 phenylpropanoic acid 1, which is known to be an effective fuel for acid-base driven molecul...

In its minimal expression, a supramolecular catalyst that acts on a single bound substrate consists of (i) a binding unit that is complementary to a non‐reacting part of the substrate, (ii) a reactive unit capable of catalyzing the reaction of the bound substrate, and (iii) a spacer connecting the two units in a geometry suitable for productive bin...

This work aimed to render phenomenologically autonomous the otherwise stepwise operation of a catenane‐based molecular switch, which is chemically triggered by the decarboxylation of 2‐cyano‐2‐phenylpropanoic acid (2). Given that any amount of 2 in stoichiometric excess with respect to the catenane is consumed in a side reaction, the authors resort...

Back and forth motions of the acid‐base operated molecular switch 1 are photo‐controlled by irradiation of a solution which also contains the photolabile prefuel 4. The photo stimulated deprotection of the prefuel produces controlled amounts of acid 2 whose base‐promoted decarboxylation fuels the back and forth motions of the Sauvage type [2]‐caten...

This work deals with the use of 2-cyano-2-arylpropanoic acids as chemical fuels for an acid-base operated molecular switch, that consists in a Sauvage-type catenand composed of two identical macrocycles incorporating a phenanthroline unit. When used as a base promoter of the decarboxylation of the propanoic acid derivatives, the switch undergoes la...

An imidazo[1,5-a]pyridine derivative was unexpectedly obtained through the action of Fe2+ on a dynamic library of imines generated in situ via condensation of benzaldehyde and 2-picolylamine. The reaction product was easily isolated as the only nitrogen-containing product eluted from the chromatographic column. A reaction mechanism is proposed, in...

The cone-calix[4]arene derivative (1H3)2+, decorated at the upper rim with two guanidinium units and a phenolic hydroxyl in an ABAH functionalization pattern, effectively promotes the cleavage of the DNA model compound bis(p nitrophenyl) phosphate (BNPP) in 80% DMSO solution, at pH values in the range 8.5 – 12.0. The pH dependence of the kinetics w...

The decarboxylation of 2-cyano-2-phenylpropanoic acid is fast and quantitative when carried out in the presence of 1 molar equivalent of a [2]catenane composed of two identical macrocycles incorporating a 1,10-phenanthroline unit in their backbone. When decarboxylation is over, all of the catenane molecules have experienced large-amplitude motions...

The catalytic activity of an artificial phosphodiesterase that combines a ligated metal ion (CuII, ZnII) with a guanidinium unit connected by a 1,2 vicinal calix[4]arene spacer was investigated in the transesterification of RNA models HPNP and four diribonucleoside 3',5'monophosphates. Comparison with the previously reported catalytic data related...

The decarboxylation of 2-cyano-2-phenylpropanoic acid is fast and quantitative when carried out in the presence of 1 molar equivalent of a [2]catenane composed of two identical macrocycles incorporating a 1,10-phenanthroline unit in their backbone. When decarboxylation is over, all of the catenane molecules have experienced large-amplitude motions...

A 22-membered cyclic alkene C1 incorporating an exotopic 1,10-phenanthroline nucleus in the ring skeleton has been synthesized and subjected to ring-opening metathesis polymerization (ROMP) in dilute dichloromethane solution at varying monomer concentrations (cmon). The resultant libraries of macrocyclic oligomers were used as ligands for the gener...

A cone-calix[4]arene derivative, featuring a guanidinium group and a CuII ion ligated to a 1,4,7 triazacyclononane (TACN) ligand at the 1,3-distal positions of the upper rim, effectively catalyzes the cleavage of 2-hydroxypropyl p-nitrophenyl phosphate (HPNP) and a number of diribonucleoside 3',5'-monophosphates (NpN?). Kinetic and potentiometric m...

A dilute (30 mM) dichloromethane solution of the copper(I) complex 1·Cu+ of a [2]-catenane composed of two identical 28-membered macrocyclic alkenes featuring a phenanthroline moiety in the backbone was subjected to ring-opening metathesis polymerization (ROMP) with second-generation Grubbs catalyst. Shortly after mixing of reactants, the dark red...

Reactivity data relating to bimolecular reactions of compounds featuring complementary recognition sites are critically surveyed and discussed in terms of effective molarity (EM) as an absolute measure of the efficiency of the intracomplex reactions. Comparison of experimentally determined EM values with idealized values estimated for strain-free c...

A new strategy for determining thermodynamic effective molarities (EM) for macrocylisation reactions using dynamic combinatorial chemistry under dilute conditions is presented. At low concentrations, below the critical value, Dynamic Libraries (DLs) of bifunctional building blocks contain only cyclic species, so it is not possible to quantify the e...

Calix[4]arenes derivatives 1 and 2, featuring two guanidine units at the upper rim, catalyze the transesterification of diribonucleoside monophosphates much more effectively than that of HPNP. Rate accelerations relative to background range from 10^3 to 10^4-fold, and approach 10^5-fold with the most favorable substrate-catalyst combinations.

Nonheme iron complex 1 is easily obtained by one-pot assembly of cheap and commercially available starting materials. This complex effectively catalyzes the oxidation of a number of non-activated C–H bonds by H2O2 with high turnover numbers and good selectivity.

Olefin cross-metathesis of diluted dichloromethane solutions (≤0.15 M) of the 28-membered macrocyclic alkene , featuring a 1,10-phenanthroline moiety in the backbone, as well as of catenand , composed of two identical interlocked units, generates families of noninterlocked oligomers Ci. The composition of the libraries is strongly dependent on the...

This paper reports on a quantitative investigation of rates of amine-imine exchange reactions of primary amines with their benzylidene derivatives in organic solvents at room temperature. Exchange reactions involving aromatic-aromatic or aromatic-aliphatic amines were in all cases fast enough to allow their use in the effective catalysis of imine m...

The catalytic activity and the selectivity of new bipyrrolidine based Fe(II) complexes 2.Fe(OTf)2 and 3.Fe(OTf)2 in the oxidation of a series of alkyl and alkenyl hydrocarbons as well as of an aromatic sulfide with H2O2 were tested and compared with the catalytic efficiency of White's parent complex 1.Fe(OTf)2 in order to evaluate the sensitivity o...

Examples of reactivity of carbonyl and phosphoryl compounds controlled by calixarenes are illustrated in this review article. The molecular framework of calixarenes has been widely used as a versatile molecular platform for the dynamic arrangement of one or more structural units working as recognition and/or catalytic sites, in many cases with cons...

Diphenylmethane derivatives 1-3, decorated with two guanidine units, are effective catalysts of HPNP transesterification. Substitution of the methylene group of the parent diphenylmethane spacer with cyclohexylidene and adamantylidene moieties enhances catalytic efficency, with gem dialkyl effect accelerations of 4.5 and 9.1, respectively. Activati...

Amine–imine exchange reactions of sterically unhindered reactants were found to be surprisingly fast at room temperature in a variety of nonaqueous solvents in the absence of proton and metal catalysts. The reaction mechanism suggested by ab initio calculations in the gas phase involves nucleophilic addition to the C]N bond in concert with proton t...

The upper rim cone tetraguanidinocalix[4]arene is a highly effective catalyst of ATP hydrolysis. The catalytically most active species is the triprotonated form of the catalyst. The three protonated guanidinium groups provide the electrostatic driving force for substrate binding and activation, while the neutral guanidine most likely acts as a nucl...

The binding affinities of tetramethylammonium chloride to uranyl salophen receptors decorated with X-substituted aromatic pendants (X = OCH3, CH3, H, Br, NO2) point to the importance of resonance effects in cation–π interactions, at variance with the view that field/inductive effects play a dominant role.

The 1,3-distal cone-calix[4]arene dialdehyde 1 undergoes Cannizzaro disproportionation in the presence of strong base, but its 1,2-vicinal regioisomer 3 and the analogous monoaldehyde 2 are unreactive under the same conditions. The high intramolecular reactivity of the 1,3-distal regioisomer 1 is measured and discussed in terms of Effective Molarit...

Calix[4]arene derivatives, blocked in the cone conformation and functionalized with two to four guanidinium units at the upper rim were synthesized and investigated as catalysts in the cleavage of the RNA model compound 2-hydroxypropyl p-nitrophenyl phosphate. When compared with the behavior of a monofunctional model compound, the catalytic superio...

The perturbation caused by a silver template on the composition of a DCL of cyclophane formaldehyde acetals was investigated as a function of monomer concentration ranging from dilute solutions to values approaching the critical monomer concentration. The target-induced amplification of the dimeric macrocycle was quantitatively analyzed in terms of...

Artificial phosphodiesterases that combine a guanidinium unit with a general base connected by a m-xylylene linker catalyze the transesterification of the RNA model compound 2-hydroxypropyl p-nitrophenyl phosphate (HPNP). The bifunctional catalysts presented in this work show varying extents of cooperation between catalytic units and a rate enhance...

Photochemical interconversion of the two diastereoisomers cis- and trans-thianthrene dioxide (1) can be considered an example of photodynamic combinatorial chemistry (PDCC) in which the interconversion among diastereomeric equilibrating species is brought about by electromagnetic irradiation. Photoequilibrium can be shifted by irradiation at differ...

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BAL2 demethylation of 2-(methoxycarbonyl)-1,3-xylylene-18-crown-5 by benzenemethanethiolate anion in dimethylformamide (+ 1.6M water) at 35°C is significantly promoted by alkali-metal counterions, the efficiency order being Na+ > K+ > Cs+ > Li+. The contrasting behaviour of the model compound, methyl 2,6-dimethylbenzoate, whose demethylation reacti...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

IntroductionCalixarenes as HostsCalixarenes as Molecular PlatformsConcluding RemarksReferences

Dynamic libraries of cyclophane formaldehyde acetals were generated from mixtures of two different monomeric units and quantitatively analyzed for the equilibrium concentrations of the lower cyclic oligomers. Plots of equilibrium concentration versus total monomer concentration exhibited saturation behaviors analogous to those observed in the equil...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The Et(3)N-assisted addition of beta-ketoester 3 to MVK in chloroform is catalyzed with high turnover efficiency by the phenyl-substituted uranyl-salophen compound 2b but not by the parent compound 1b. A plausible mechanism is suggested, involving concomitant nucleophilic attack at the beta-carbon and hydrogen bonding between the Et(3)NH(+) counter...

In the search for configurationally stable inherently chiral uranyl-salophen complexes, the newly synthesized compound 3 featuring a dodecamethylene chain was expected to be a promising candidate. Unexpectedly, dynamic HPLC on a enantioselective column showed that it still undergoes enantiomerization at high temperature. By comparison with the dyna...

The design and synthesis of a novel fluoride receptor that uses a salen-complexed Lewis acidic uranyl center as the sole binding site is reported here. This receptor binds fluoride anions in DMSO with a high affinity constant (K > 10(6) M(-1)) and exhibits a negligible affinity (K < 10 M(-1)) towards otherwise effective competitors, such as acetate...

The acid-catalyzed transacetalation of cyclophane formaldehyde acetals incorporating m-xylylene units (m-Ci) generates a well behaved dynamic library of oligomeric macrocycles. Effective Molarities (EM) relating to the formation of the lower cyclic oligomers (i = 2–4) were estimated from equilibrium concentrations measured under conditions closely...

Di- and trinuclear copper(II) complexes of [12]aneN3 macrocycles anchored at the upper rim of cone calix[4]arenes in 1,2-, 1,3-, and 1,2,3-positions were investigated as cleaving agents of 6-, 7-, and 17-meric oligoribonucleotides. A kinetic investigation of the cleavage reactions was carried out using gel electrophoresis to separate and analyze re...

Anthraquinone derived oxalamide gelator 1 forms with aromatic solvents and alcohols very stable gels which selectively respond to the presence of fluoride anion by colour change and/or gel-to-sol transition.

The Al(III)-salophen complex 1 exhibited strong spectroscopic changes specifically upon addition of polyG and GpG, while double stranded DNA and RNA, and single stranded polyA, polyU and polyC induced negligible spectral changes of 1. Titrations with mono-nucleotides yielded no spectroscopic changes, revealing that there must be at least two consec...

Zinc–salophen compounds 1–3 incorporating in the given order 1,2-diaminobenzene, 2,3-diaminonaphthalene, and 9,10-diaminophenantrene moieties were synthesised. Their binding properties toward a series of tertiary amines were assessed by UV-Vis and fluorescence spectroscopy in chloroform solution. Unprecedented selectivities of quinuclidine vs. trie...

The Et3N-assisted addition of benzenethiol to enones in chloroform is catalyzed with high turnover efficiency by the phenyl-substituted uranyl-salophen compound 3. Catalytic data show a close adherence to a quatermolecular mechanism involving reaction of a base-activated thiol with a reversibly formed complex of enone and metal catalyst, with a com...

Efficient ditopic receptors for quaternary ammonium and iminium salts have been obtained upon functionalization of the uranyl-salophen unit with conformationally flexible side arms bearing phenyl or beta-naphthyl substituents. Binding affinities in chloroform solution have been measured for a large number of quaternary salts comprising tetramethyla...

The catalytic activity of the zinc(II) complexes of calix[4]arenes decorated with 1,5,9-triazacyclododecane ligands at the 1,2-, 1,3-, and 1,2,3-positions of the upper rim was investigated in the basic methanolysis (pH 10.4) of aryl acetates functionalised at the meta- and para-positions with a carboxylate anchoring group. Michaelis–Menten kinetics...

Crown ether macrocycle 1 including a zinc-salophen unit is obtained via a de novo synthetic design to give a potential pH-driven two-stationed wheel component of [2]-pseudorotaxane systems.

Important insight has been obtained into the mechanism of the reversible acid-catalysed transacetalation of cyclophane formaldehyde acetals (formals) C(i) in CDCl(3), at 25 degrees C. The order of appearance of the lowest oligomers in the early stages of the equilibration reaction is fully consistent with ring-fusion/ring-fission processes in which...

Calix[4]arenes functionalized at the 1,2-, 1,3-, and 1,2,3-positions of the upper rim with [12]ane-N(3) ligating units were synthesized, and their bi- and trimetallic zinc(II) and copper(II) complexes were investigated as catalysts in the cleavage of phosphodiesters as RNA models. The results of comparative kinetic studies using monometallic contro...

Complexation of CsF with the ditopic uranyl-salen receptor results in a solid-state structure, in which the coordination sphere of cesium is filled by ligation to one of the chlorine atoms of the solvent chloroform. This X-ray structure is the first example of chloroform ligation to an alkali-metal ion.

[structure: see text] A flipping motion rapidly inverts the bent structure of uranyl-salophen compounds and, consequently, causes fast enantiomerization of nonsymmetrically substituted derivatives. This process has been previously slowed by introducing bulky substituents in the imine bond region. Since the resulting complexes dissociate upon chroma...

[structure: see text] The stereomutations in nonsymmetrical salophen ligands 1-4 were studied by means of dynamic NMR and HPLC methods. DNMR experiments showed that in DMSO-d(6) hindered ligands 2-4 exist in two chiral conformations, depending on whether the imine carbon atoms are in a cis or trans disposition with respect to the plane of the centr...

The acid-catalyzed transacetalation of formaldehyde acetals (formal metathesis) is a suitable reaction for the generation of well-behaved Dynamic Libraries of cyclophane formals. The composition of the equilibrated mixtures solely depends on concentration, and is totally independent of whether the feedstock is any of the pure cyclic oligomers, or a...

Whereas the parent uranyl salophen is catalytically inactive, its phenyl derivative effectively catalyses with turnover the reaction of benzoquinone with 1,3-cyclohexadiene, while showing no appreciable affinity towards reactants and product.

[structures: see text] The kinetics of methanolysis of a number of esters endowed with a carboxylate anchoring group have been investigated in the presence of di- and trinuclear Zn2+ complexes of calix[4]arenes functionalized at the upper rim with nitrogen ligands. The results (i) emphasize the importance of a good match between ester size and inte...

Hard anions have long been known to bind strongly to the uranium of uranyl-salophen complexes. Upon functionalization of the salophen framework with one or two benzyloxy substituents, efficient ditopic receptors for alkali metal ions are obtained. The solid-state structures of complexes formed by the two-armed receptor 1 with CsF and with the chlor...

The calix[4]arene scaffold, blocked in the cone conformation by proper alkylation of the lower rim hydroxyls, was used as a convenient molecular platform for the design of bi- and trimetallic Zn2+ catalysts. The catalytic activity of the Zn2+ complexes of calix[4]arenes decorated at the 1,2-, 1,3-, and 1,2,3-positions of the upper rim with 2,6-bis[...

The calix[4]arene scaffold, blocked in the cone conformation by proper alkylation of the lower rim hydroxyls, was used as a convenient molecular platform for the design of bi- and trimetallic Zn2+ catalysts. The catalytic activity of the Zn2+ complexes of calix[4]arenes decorated at the 1,2-, 1,3-, and 1,2,3-positions of the upper rim with 2,6-bis[...

Two novel regioisomeric calix[4]arene derivatives (2 and 3), decorated with two aza[18]crown-6 units at vicinal (1,2) or diagonal (1,3) positions of the upper rim, were synthesized. The catalytic activities of their dinuclear Ba2+ complexes were investigated in the ethanolysis of esters 8-11, endowed with a carboxylate anchoring group. Major result...

“Inherent chirality” in molecules like calix[4]arenes, fullerenes, and uranyl-salophen complexes can be related to the presence of curvature. This observation serves as a basis for the introduction of a new chirality descriptor.

The first diastereoisomeric mixture of an inherently chiral uranyl-salophen complex was prepared using (S)-naproxen as a chiral derivatizing agent. Slow crystallization from diisopropyl ether-chloroform afforded one pure diastereoisomer in 45% yield. Kinetic studies allowed the determination of the epimerization rate. [reaction--see text]

We have shown that the Cu II complexes of the concave ligand 1 and its model compound 2 are efficient catalysts of ester methanolysis under conditions close to neutrality. Turnover catalysis without product inhibition was demonstrated by the clean first‐order release of a greater than stoichiometric amount of product. Compared with background metha...

Reactivity data related to processes in which molecular receptors promote the reaction of two simultaneously complexed reactants have been surveyed and analyzed in terms of effective molarity (EM). Methods and criteria for the calculation of reliable EM's have been highlighted. Extension of a previous extrathermodynamic treatment of intramolecular...

Three novel polyoxyethylene bridged bis phenol A derived cyclophanes, with additional aromatic units in the bridge to increase the number of cation–π interactions with guest cations, were synthesized and characterized by means of X-ray crystal structure determinations. The binding properties of these receptors toward tetramethylammonium (TMA), N-me...

Uranyl-salophen complexes endowed with aromatic side arms behave as very efficient ditopic receptors towards tetralkylammonium halides as a result of a combination of Lewis acid-base and cation-pi interactions.

In complexes with the uranyl dication salophen ligands are highly puckered. This implies that non-symmetrically substituted uranyl-salophen derivatives exist in principle as a pair of enantiomers. However, due to easy disrotations about the bonds connecting the phenoxide units to the imine carbons, the rate of interconversion between enantiomeric f...

The synthesis and isolation of elusive tetralkoxycalix[4]arenes 2 in the cone conformation and bearing two formyl groups in proximal (1,2) positions at the upper rim are described for the first time. They were obtained as a mixture with the distal (1,3) regioisomers 3 by optimizing the Gross formylation reaction on the tetralkoxycalix[4]arenes 1. A...

Reversible phototuning of the catalytic efficiency of the bis-barium complex of azobis(benzo-18-crown-6) in the basic ethanolysis of anilide derivatives has been achieved by light-induced cis right arrow over left arrow trans interconversion of the azobenzene spacer unit of the catalyst. The geometry of the productive catalyst-substrate complex is...

The cover picture shows the four-body productive complex involved in the rate-determining step of the addition of a triethylamine-activated benzenethiol to a uranyl−salophenactivated 2-cyclopenten-1-one. The background offers a view of the complex rate equation ad hoc developed for the above (two reactant)-(two catalyst) system involving complexati...

A thorough kinetic investigation of the triethylamine-catalysed addition of benzenethiol to 2-cyclopenten-1-one in chloroform shows that the highest energy transition state is a complex of thiol, enone, and base in a 1:1:1 ratio, but whether formation or disruption of the enolate−triethylammonium ion-pair intermediate is rate-limiting is uncertain....

[reaction: see text] A series of 6-exo-acetoxybicyclo[2.2.2]octan-2-ones were converted into the corresponding 6-exo-hydroxybicyclo[2.2.2]octan-2-ones by methanolysis in the presence of CH(3)ONa/La(OTf)(3). Under the given conditions, epimerization at C(6) of the latter led in the least favorable cases only to traces of the more stable 6-endo-hydro...

The complexation of the salophen-uranyl metallocleft 2 and of its half-cleft analogue 3 with enones and other carbonyl compounds was assessed in chloroform by UV-Vis titration and, occasionally, by FT-IR measurements. Complexes with receptors 2 and 3 are in all cases more stable than those with the control unsubstituted uranyl-salophen 1 , showing...

The basic ethanolysis of esters and anilides endowed with a distal carboxylate anchoring group is catalyzed by the dinuclear Ba(II) complexes of cis- and trans-stilbenobis(18-crown-6). Comparison with the catalytic efficiency of a mononuclear model catalyst demonstrates that the two metal ions in the dinuclear complexes act synergically. The cis fo...

Two novel neutral polyoxyethylene bridged cyclophanes (2a and 2b) incorporating bisphenol A units were synthesized and characterized by means of x-ray crystal structure determination. The binding properties of 2a and 2b toward tetramethylammonium, N-methylpyridinium, and acetylcholine cations were evaluated by means of 1H NMR spectroscopy. Consiste...

A number of neutral cyclophanes incorporating either a 2,6- or a 2,7-dioxynaphthalene unit have been synthesised and their binding properties toward tetramethylammonium and N-methylpyridinium picrates assessed by means of a H NMR spectroscopic technique. A parallel computational study based on molecular mechanics and molecular dynamics calculations...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The synthesis and structural characterisation of three new macrocyclicbis-phenol A cyclophane ethers are described. The solid state structuresof two of the cyclophanes were determined by single crystal X-raydiffraction. Cyclophane 3 crystallises in the orthorhombic spacegroup Pbca with unit cell dimensions of a = 11.533(7), b = 29.383(8),c = 14.927...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The methanolysis of choline p-nitrophenylcarbonate in chloroform containing 1% methanol is catalyzed with turnover by ditopic receptors 1 and 2, consisting of a calix[6]arene connected to a bicyclic guanidinium by means of a short spacer. The calix[6]arene subunit strongly binds to the trimethylammonium head group through cation-pi interactions, wh...

The methanolysis of choline p-nitrophenylcarbonate in chloroform containing 1% methanol is catalyzed with turnover by ditopic receptors 1 and 2, consisting of a calix[6]arene connected to a bicyclic guanidinium by means of a short spacer. The calix[6]arene subunit strongly binds to the trimethylammonium head group through cation - π interactions, w...

The role of ring strain on the ease of ring formation over a wide range of ring sizes is discussed on the basis of a comparison of transition state versus product-ring strain energies. A general procedure is illustrated for the assessment of transition-state strain energies, based on experimental effective molarities (EMs) and an extra-thermodynami...

The scope of the barium salt of p-tert-butylcalix[4]arene-crown-5 as a transacylation catalyst has been defined by evaluating its efficiency in the methanolysis of a series of aryl acetates at 25.0 degrees C in MeCN/MeOH 9:1 (v/v) under slightly basic conditions. In this system a phenolic hydroxyl is the acyl-receiving and -releasing unit in a doub...

The base induced addition of benzenethiol to 2-cyclohexen-1-one and its 4,4-, 5,5- and 6,6-dimethyl derivatives is catalysed by a salophen-uranyl based metallocleft 2 in chloroform solution with high turnover efficiency and low product inhibition. Analysis of rate data coupled with equilibrium measurements for complexation of the catalyst with the...

The triethylamine-catalyzed addition reactions of benzenethiol to 2-cyclopenten-1-one and its 2- and 3-methyl derivatives have been found to be appreciably reversible in chloroform solution. Rates and equilibria have been carefully measured at 25 degrees C in order to assess the negative influence on addition exerted by methyl groups substituted on...

The reversible acid/base-(hydrogen-bonding-) controlled association between racemic crown ethers incorporating a binaphthyl unit (the socket) and wirelike compounds bearing an anthracenyl unit (the plug) is described. The compounds used were the (±)binaphthocrown ethers BN20C6, BN23C7, and BN26C8, the amines 9-methyl(aminomethyl)anthracene (AM) and...