Ornelio Rosati

Università degli Studi di Perugia | UNIPG · Department of Pharmaceutical Science

Functionalized primary, secondary and tertiary alcohols are efficiently acetylated by isopropenyl acetate and catalytic p-TsOH.

Silyl enol ethers are extremely useful nucleophilic intermediates for chemical transformations because they are synthetically versatile substrates for a wide range of C–C bond-forming reactions. Here, we present a new, mild, and solvent-free procedure for the synthesis of silyl enol ethers that employs a catalytic amount of solid-supported base and an equimolar amount of N,O-(bistrimethylsilyl)acetamide as a silylating agent.

The one-pot three component reaction between dimedone derivatives, malonitrile or cyanoacetate and aryl, alkenyl or alkyl aldehydes provides the title products in generally high yields.

No abstract is available for this article.

A high-yielding, one-pot, three-component synthesis of functionalized 2-amino-4H-pyrans from β-dicarbonyl compounds, activated cyanomethylene compounds, and aldehydes, mediated by potassium-exchanged zirconium hydrogen phosphate [α-Zr(KPO4)2], is reported. The protocol shows excellent versatility, as it can be applied to aromatic, aliphatic, or α,β-unsaturated aldehydes under solvent-free conditions.

An efficient, chemoselective homologation of disulfides and diselenides to the corresponding dithio- and diselenoacetals has been developed via the addition of bromomethyllithium. Chemoselectivity is fully preserved in the presence of concomitant electrophilic sites decorating the substrates. The synthetic potential of selected dithioacetals has been evaluated in Feringa-Fañanas-Mastral-type Pd-catalyzed coupling with an organolithium and in the unusual 1,4-addition to a Weinreb amide.

A selenium-mediated strategy for the stereoselective synthesis of substituted tetrahydropyrans and isochromans has been developed starting from delta-phenylseleno ketones. After enantioselective reduction, the chiral non-racemic phenylseleno alcohols were oxidized to the corresponding selenones which underwent an efficient 6-exo-tet ring-closure reaction.

The therapeutic use of Cannabis dates back to ancient times and this plant has been used for centuries as remedy for a large number of diseases. Today it is well known that biological activity of Cannabis is related to the endocannabinoid system (ECS), a complex signaling network that comprises classical cannabinoid receptors (CB1 and CB2), arachidonic acid-derived ligands, and enzymes degrading the endocannabinoids anandamide and 2-arachidonoyl glycerol, namely fatty acid amide hydrolase and monoacylglycerol lipase. The modulation of the ECS activity turned out to be a therapeutic promise in a wide range of diseases. A problem to the development of Cannabis and cannabinoid medications is the psychoactive property of natural or synthetic agonists, mediated by CB1 receptor. This review deals with the literature analysis of the important biological activities of Cannabis and the efforts aimed to the discovery of natural and nonnatural selective cannabinoids.

Δ(9)-tetrahydrocannabinol (Δ(9)-THC) is the major psychoactive cannabinoid in hemp (Cannabis sativa L.) and responsible for many of the pharmacological effects mediated via cannabinoid receptors. Despite being the major cannabinoid scaffold in nature, Δ(9)-THC double bond isomers remain poorly studied. The chemical scaffold of tetrahydrocannabinol can be assembled from the condensation of distinctly substituted phenols and monoterpenes. Here we explored a microwave-assisted one pot heterogeneous synthesis of Δ(3)-THC from orcinol (1a) and pulegone (2). Four Δ(3)-THC analogues and corresponding Δ(4a)-tetrahydroxanthenes (Δ(4a)-THXs) were synthesized regioselectively and showed differential binding affinities for CB1 and CB2 cannabinoid receptors. Here we report for the first time the CB1 receptor binding of Δ(3)-THC, revealing a more potent receptor binding affinity for the (S)-(-) isomer (hCB1Ki = 5 nM) compared to the (R)-(+) isomer (hCB1Ki = 29 nM). Like Δ(9)-THC, also Δ(3)-THC analogues are partial agonists at CB receptors as indicated by [(35)S]GTPγS binding assays. Interestingly, the THC structural isomers Δ(4a)-THXs showed selective binding and partial agonism at CB2 receptors, revealing a simple non-natural natural product-derived scaffold for novel CB2 ligands.

Substrates with electron-withdrawing groups give the undesired hemiacetal (V) as major product.

A new, efficient and mild method for the direct oxidation of selenides to selenones using magnesium bis(monoperoxyphthalate) hexahydrate (MMPP) has been developed. Noteworthy this transformation proceeds at room temperature, employs a cheap and safety oxidant and has a broad functional group tolerance. Moreover, the produced selenones could be useful intermediates for the synthesis of different heterocyclic compounds.

Agarsenone (1), a new cadinane sesquiterpenoid, was isolated from the resin of Commiphora erythraea. The structures of 1 and its decomposition products agarsenolides (2a and 2b) and myrrhone (3) were established by extensive NMR spectroscopic analysis. The absolute configuration of 3 and the relative and absolute configurations of 1 were assigned by comparison of experimental and calculated optical rotatory dispersion and electronic circular dichroism spectra. © 2013 The American Chemical Society and American Society of Pharmacognosy.

According to the Green Chemistry principles, water is the first choice solvent to reduce chemical waste and environmental impact of chemical industry. Reaction in water can be improved when microwave irradiation is applied to a synthetic procedure due to the possibility to reach temperatures higher than the boiling point. This is especially true when reactions are carried out in superheated/ subcritical conditions (over 100 °C). In this paper, several synthetic procedures that use superheated or subcritical water as solvent in sealed vials under microwave irradiation as heating system, are reviewed. Noteworthy, the targets of these synthesis are valuable compounds of pharmaceutical interest.

A new cyathane diterpene, cyrneine E (1) was isolated from the mushroom Sarcodon cyrneus. The structure of the novel compound was determined by analysis of its spectroscopic data.

Layered α-zirconium sulfophenylphosphonate-methanphosphonate is a solid acid catalyst that catalyzes Ferrier rearrangement from d-glycals and alcoholic nucleophiles under mild reaction conditions in short time and good yields. Notably, the combination of α-zirconium sulfophenylphosphonate-methanphosphonate and lithium bromide change the regioselectivity of this process affording 2-deoxy sugars in good yields. Graphical Abstract

Here we report a sustainable protocol for the cyanosilylation of carbonyl compounds 1a–g and 3a–m using trimethylsilyl cyanide and triphenylphosphine supported on polystyrene as a catalyst under solvent-free conditions. It has been shown that a small amount of the catalyst allows the chemoselective 1,2-addition of trimethylsilyl cyanide to α,β-unsaturated carbonyls 1a–g (5 mol%) and to saturated carbonyls 3a–m (2 mol%). The preparation of cyanohydrin trimethylsilyl ethers 2a–g and 4a–m has been accomplished in good yields (72–99%) and very low E-factor values (5–10). Finally, efficiency has been further improved by setting two different flow procedures that have allowed us to perform the representative preparation of cyanohydrin trimethylsilyl ether 4a on a large scale and with the E-factor of 0.16 or 0.47 consisting in a reduction of 90 or 72% of waste compared to our batch conditions.

Organosulphur compounds can be easily and selectively oxidized to sulfones using a small excess of Oxone® (1.6 eq.) under solventless mechanical milling conditions. This green procedure has been efficiently applied to a series of model compounds and to the desulphurization of medium/high sulphur content paraffins (up to 3000 mg kg(-1)).

Cinnabarinic acid is an endogenous metabolite of the kynurenine pathway that meets the structural requirements to interact with glutamate receptors. We found that cinnabarinic acid acts as a partial agonist of type 4 metabotropic glutamate (mGlu4) receptors, with no activity at other mGlu receptor subtypes. We also tested the activity of cinnabarinic acid on native mGlu4 receptors by examining 1) the inhibition of cAMP formation in cultured cerebellar granule cells; 2) protection against excitotoxic neuronal death in mixed cultures of cortical cells; and 3) protection against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine toxicity in mice after local infusion into the external globus pallidus. In all these models, cinnabarinic acid behaved similarly to conventional mGlu4 receptor agonists, and, at least in cultured neurons, the action of low concentrations of cinnabarinic acid was largely attenuated by genetic deletion of mGlu4 receptors. However, high concentrations of cinnabarinic acid were still active in the absence of mGlu4 receptors, suggesting that the compound may have off-target effects. Mutagenesis and molecular modeling experiments showed that cinnabarinic acid acts as an orthosteric agonist interacting with residues of the glutamate binding pocket of mGlu4. Accordingly, cinnabarinic acid did not activate truncated mGlu4 receptors lacking the N-terminal Venus-flytrap domain, as opposed to the mGlu4 receptor enhancer, N-phenyl-7-(hydroxyimino)cyclopropa[b]chromen-1a-carboxamide (PHCCC). Finally, we could detect endogenous cinnabarinic acid in brain tissue and peripheral organs by high-performance liquid chromatography-tandem mass spectrometry analysis. Levels increased substantially during inflammation induced by lipopolysaccharide. We conclude that cinnabarinic acid is a novel endogenous orthosteric agonist of mGlu4 receptors endowed with neuroprotective activity.

New highly soluble β-aminoalcohol β-cyclodextrin (β-CD) derivatives have been synthesized via nucleophilic epoxide opening reactions with mono-6-amino mono-6-deoxy-permethyl-β-CD and mono-6-amino mono-6-deoxy-β-CD. The binding properties of the β-CD were enhanced by linking aminoalcohol subunits which caused its solubility to improve markedly. The reaction conditions were optimised using microwave irradiation giving moderate-to-good yields with a series of epoxides. A regioselective epoxide opening reaction was observed in the reaction with styrene oxide while the stereoselectivity was strictly dependent on substrate structure.

Abstract3,4-Dihydropyrimidin-2(1H)-one derivatives were synthesized using layered α-zirconium sulfophenylphosphonate as a recyclable heterogeneous catalyst. Several classes of reagents, such as functionalized aromatic and aliphatic aldehydes, β-dicarbonyl derivatives and 2-aminobenzimidazole, were used to synthesize different 3,4-dihydropyrimidin-2(1H)-one derivatives under solvent free conditions. Graphical Abstract KeywordsHeterogeneous catalysis–Multicomponent reaction–Heterocycles–Biginelli reaction–3,4-dihydropyrimidin-2(1H)-ones

AbstractAn efficient one-pot synthesis of 3,4,5-trisubstituted-3,6-dihydro-2H-1,3-oxazines from acetylene dicarboxylates, aromatic and aliphatic amines, and formaldehyde is described. The six member N,O-heterocyclic nucleus was constructed via Yb(OTf)3 promoted domino hydroamination/Prins reaction/cyclization/dehydration reactions. Graphical Abstract KeywordsHeterogeneous catalysis–Multicomponent reactions–Lanthanides–Oxazine derivatives–Ytterbium triflate

Ytterbium triflate was shown to be effective in promoting the synthesis of substituted indole derivatives starting from indole, aldehydes, and dimethyl malonate by a Yonemitsu-type three component reaction. The whole process was carried out in solvent-free conditions and furnished the desired adducts in 42–67% yield.

Rh2(OAc)4-assisted decompositions of diazoacetylcycloalkanes are shown to yield cycloalkylacetic acids (Wolff rearrangement), unexpected cycloalkylcarboxylic acids and bicyclic ketones (intramolecular CH bond insertion). Rh2(OCOCF3)4-promoted reactions, on the other hand, have furnished bicyclic ketones and ketene dimers.

The interaction of trisubstituted olefins with excess phenylselenenyl chloride in methanoi generates chloromethoxy dimethoxyderivatives. The mechanism of this transformation has been investigated.

A mild and efficient process for one-step conversion of oximes into gem-halo-nitro compounds using Oxone® and sodium chloride or potassium bromide is described.

Zirconium Sulfophenyl Phosphonate Zr(O3PCH3)(1.2)(O3PC6- InSO3H)(0.8) was found to be an efficient heterogeneous catalyst for the tetrahydropyranylation of alcohols and phenols.

The reaction of various coumarins with cyanoacetamide derivatives under basic conditions (sodium ethoxide, piperidine or 2,2,6,6-tetramethylpiperidine), proceeds via an interesting process which involves skeletal rearrangement of the coumarin, a Michael addition and two cyclizations to afford 5-amino-1,10b-dihydro-2H-chromeno[3,4-c]pyridine-2,4(3H)-diones. The same reaction in the presence of N,N'-ethane-1,2-diylbis(2-cyanoacetamide) gives the corresponding mono and bis 5-amino-1,10b-dihydro-2H-chromeno[3,4-c]pyridine-2,4(3H)-diones.

Er(OTf)3 is proposed as a highly efficient and reusable catalyst for the opening of epoxides in water with aliphatic as well as aromatic amines leading to the synthesis of β-amino alcohols. The aqueous conditions employed in the present method will make it ‘environmentally friendly’ and potentially useful for industrial applications.

New heterogeneous catalysts for liquid phase organic synthesis have been obtained by precipitating MgAl-hydrotalcites like compounds according to the urea method in the presence of Sn(IV) and characterised for their composition, thermal behaviour, X-ray diffraction pattern and B.E.T. specific surface area. The anion exchange capacity of the solids has been determined to have information on the possible incorporation of Sn(IV) into the brucite layer of the hydrotalcites. The values obtained give support to the hypothesis that most part of Sn(IV) is present as co-precipitated hydrous oxide. The base strength surface sites was estimated with the method of adsorbed acid–base indicators and the samples have been used as heterogeneous catalysts in the preparation of 4H-chromenes. The results obtained showed that MgAl-hydrotalcite doped with Sn(IV) catalyses the tandem Knoevenagel–Michael reactions, giving good to excellent yields in short time and its performance has been compared with that of the corresponding MgAl-hydrotalcite. Moreover, the catalyst was recovered and reused several times without loss of activity.

This review provides the first overview on the isolation and structure elucidation of a class of isopimaric diterpenes: virescenols. An important part of this review deals with the structural modifications of virescenols leading to several different natural product frameworks.

A regioselective synthesis of 2,3-disubstituted tetrahydro-2H-indazols, mediated by alpha-zirconium sulfophenylphosphonate-methanephosphonate, was reported. Docking studies into the catalytic site of COX-2 were used to identify potential anti-inflammatory lead compounds. Two lead derivatives were chosen endowed with good binding energies and good ADME profiling. The biological in vivo evaluation of these compounds in two different experimental models (Freund's adjuvant-induced arthritis and carrageenan-induced oedema) proved the presence of anti-inflammatory activity. Noteworthy, both compounds evidenced the lack of any gastric injury even at high doses in gastric ulcerogenic assays.

In this study, sn-1,2-, sn-2,3-, and sn-1,3-diacylglycerols were isolated from olive oil, and their urethane derivatives (urethanes) were prepared. Normal-phase high-performance liquid chromatography (NP-HPLC) separation of the urethane isomers was performed and the separate classes were studied by nuclear magnetic resonance (NMR). The use of 1H NMR and homo- and heteronuclear 2D techniques provided a great amount of information in a very short time, particularly when a high-field NMR instrument (700 MHz) was used. Particularly diagnostic for this kind of compound was the glyceridic moiety that presents typical chemical shifts both for carbon and hydrogen. These studies show the usefulness of NMR spectroscopy to recognize clearly the sn-1,3- and, moreover, sn-1,2- with respect to sn-2,3-diacylglycerols, although very minor differences occur between them.

Potassium exchanged layered zirconium phosphate catalyzed Knoevenagel condensation of aldehydes and active methylene compounds gave the corresponding E configurated olefinic derivatives in solvent free conditions.

Dehydrocholic acid (DHCA), an unnatural bile acid, is manufactured by oxidation of cholic acid. Its biotransformation by two basidiomycetes (Trametes hirsuta and Collybia velutipes) is reported. These mycelia showed different affinities for the substrate and selectivities of attack: T. hirsuta in particular regio- and stereoselectively reduced the 3-keto group to yield 3 alpha-hydroxy-7,12-diketo-5 beta-cholan-24-oic acid (7,12-diketolithocolic acid) as the main product. A number of different chemical reductions were carried out on DHCA; among them hydrogenation with Raney Nickel in water under high-intensity ultrasound proved highly regio- and stereoselective, yielding 7,12-diketolithocolic acid exclusively. (1)H and (13)C resonances were assigned in details thanks to a series of 1D and 2D NMR runs including DEPT, NOESY, H-H COSY, gHSQC and gHMBC.

The reaction of coumarin with cyanoacetate derivatives in the presence of a nucleophilic base (alkoxides or piperidine) follows an interesting pathway that involves both a coumarin skeletal rearrangement and a Michael addition, via a coumaric acid derivative, to afford a substituted 4H-chromene skeleton. The particular behavior of this process influences the performance and the type of compounds that can be obtained. We demonstrate that the use of an excess of cyanoacetate affords the 4H-chromene derivative in high yield. An explanation of the mechanism involved in this process is proposed.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

A new convenient route to enantiopure 2-coumarinyloxypropanals is described: Rosenmund reduction of (R)- or (S)-2-coumarinyloxypropanoyl chlorides afforded in good yields the corresponding 2-coumarinyloxypropanals. Their subsequent aldolic condensation with 3(2H)-furanones, followed by dehydration, led to enantiopure geiparvarin analogues now being investigated as promising antitumoral compounds.

Pyrazoles and tetrahydroindazoles may be prepared by condensation of 1,3-diones and hydrazines under layered zirconium sulfophenyl phosphonate catalysis, in solvent-free conditions.

Substituted 4H-chromenes were easily prepared by reaction of salicylaldehydes and ethylcyanoacetate in solvent free conditions using potassium exchanged layered zirconium phosphate as catalyst.

[reaction: see text] Ytterbium triflate was shown to be an effective catalyst in promoting the synthesis of either isopropyl esters or free alpha-hydroxy-arylacetic acids from substituted aromatic glyoxals and aryl methyl ketones, respectively. The reaction to provide acids starting from differently substituted ketones was carried out by an environmentally friendly method using an aqueous medium as a solvent and giving the adducts in 78-99% yield without any further purification after the usual workup.

Glaucopine A (1) and B (2), two new cyathane diterpenes, have been isolated from the mushroom Sarcodon glaucopus: their structures have been determined on the basis of spectral data. Their topical anti-inflammatory activity was evaluated using the Croton oil ear test in mice: compounds 1 and 2 (1 micromol/cm2) provoked edema reduction (62 % and 55 %, respectively) similar to that induced by the reference non-steroidal anti-inflammatory drug, indomethacin (0.3 micromol/cm2, 61 % edema reduction).

Ethyl 1-methyl-2-oxocyclohexanecarboxylate (1a) and its homologue 1b were converted to hydroisobenzofuran acids 7 (via 6-[(butylsulfanyl)methylene] and epoxide derivatives), one of which furnished hexalone derivative 11 (via an intermediate diazomethyl ketone derivative). The above-mentioned starting esters were converted to ethylene ketals, the free-radical oxidations of which led to hydrobenzofuran acids. One of the latter led to a hydrindanone (via a diazomethyl ketone), whose further chemical elaboration yielded an incisterol model. A second hydrobenzofuran acid gave a cyclobutenone (via the diazomethyl ketone), which was transformed into a more-stable cyclopentenone isomer by treatment with Lewis acid.

Differently substituted benzimidazoles have been synthesised in very good yields in solvent-free conditions from o-phenylenediamine and aldehydes in the presence of Yb(OTf)3 as catalyst. The method is applicable to aromatic, unsaturated and ­aliphatic aldehydes and to substituted o-phenylenediamines without significant differences.

The choice of layered phosphates and phosphonates of tetravalent metals, mainly Zr(IV), plays a key role in the success of liquid phase heterogeneous catalysis for the preparation of useful intermediates in organic synthesis. The preparation, the chemical and thermal stability, and the structural aspects of this emerging class of inorganic and inorgano-organic materials will be reviewed with the aim to clarify their potential in heterogeneous liquid phase catalysis. The possibility of modifying their surface area and porosity and the nature of active catalytic centres by means of ion exchange, intercalation and exfoliation reactions will be also presented. Furthermore, this review will discuss the numerous efforts dedicated to the development of new synthetic methods using acidic or basic Zr(IV) phosphates and phosphonates as valuable alternative solid catalysts compared to other classes of heterogeneous catalysts. The reported methods clearly demonstrated the importance of this type of catalysis, especially for the following features: easy handling, mild reaction conditions, solvent free conditions (in many cases), simple work-up and the recyclable nature of the catalysts. Herein, we present a review of these various types of solid catalysts and their characteristics and applications in organic synthesis.

Pyrroles may be prepared by condensation of alkyl and aryl amines and 1,4-diketones (Paal–Knorr reaction) under potassium exchanged layered Zirconium phosphate and zirconium sulfophenyl phosphonate catalyst in solvent free conditions.

A simple and efficient solvent-free coupling reaction affording regioselectively trans-alpha,beta-enones from aryl alkynes and aldehydes catalysed by Yb(OTf)(3) hydrate is described.

Ni–Al hydrotalcite-like compounds, obtained by precipitation from homogeneous solution accomplished by urea hydrolysis, have been characterised for chemical composition, BET specific surface area, X-ray diffraction and thermogravimetry. The base strength of surface sites was estimated with the method of adsorbed acid–base indicators. A sample of formula [Ni0.73Al0.27(OH)2](CO3)0.135, previously dried at 150 °C, has been used as base catalyst at 60 °C in absence of solvents in the Knoevenagel condensation of different aldehydes with malononitrile and ethylcyanoacetate. Aliphatic and aromatic aldehydes easily react in these reaction conditions and the Knoevenagel adducts were obtained in excellent yield, in short time. Dimethylmalonate, having methylene groups of very low acid strength (pKa>13) did not give the adduct with benzaldehyde because of not sufficiently high base strength of the hydrotalcite-like compound. The catalyst can be recycled several times, without loss of catalytic efficiency, and its performance has been compared with that of other heterogeneous base catalysts such as zeolite A, potassium exchanged zirconium phosphate, amberlist, modified hydrotalcites.

Ni–Al hydrotalcite-like compounds, obtained by precipitation from homogeneous solution accomplished by urea hydrolysis, have been characterised for chemical composition, BET specific surface area, X-ray diffraction and thermogravimetry. The base strength of surface sites was estimated with the method of adsorbed acid–base indicators. A sample of formula [Ni0.73Al0.27(OH)2](CO3)0.135, previously dried at 150°C, has been used as base catalyst at 60°C in absence of solvents in the Knoevenagel condensation of different aldehydes with malononitrile and ethylcyanoacetate. Aliphatic and aromatic aldehydes easily react in these reaction conditions and the Knoevenagel adducts were obtained in excellent yield, in short time. Dimethylmalonate, having methylene groups of very low acid strength (pKa>13) did not give the adduct with benzaldehyde because of not sufficiently high base strength of the hydrotalcite-like compound. The catalyst can be recycled several times, without loss of catalytic efficiency, and its performance has been compared with that of other heterogeneous base catalysts such as zeolite A, potassium exchanged zirconium phosphate, amberlist, modified hydrotalcites.

Three sesquiterpene lactones were isolated from Lourteigia ballotaefolia (H. B. K.). 9beta-hydroxy-atripliciolide-8- O-tiglate ( 1) was isolated for the first time from this plant and was previously reported in Conocliniopsis prasiifolia (DC) K. et R., 9beta-hydroxy-atripliciolide-8- O-(5'-acetoxytiglate) ( 2) had been already reported in this species. The minor component, 9beta-(tigloyloxy)-atripliciolide, is a new compound. The anti-inflammatory activity of compounds 1 and 2 was evaluated using the croton oil ear test in mice.

A facile synthesis of carbamates from amines and dimethyl carbonate has been achieved using ytterbium triflate as catalyst.

The results of the reaction between ethyl diazoacetate and carbonyl compounds catalysed by lanthanide triflates are described. Aldehydes, and α-unsubstituted and α-monosubstituted cyclohexanones react to give the selective formation of α,β-epoxy esters (glycidic esters), whereas other ketones are unreactive. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Layered zirconium sulfophenyl phosphonate was found to be an efficient heterogeneous catalyst for the preparation and deprotection of 1,1-diacetates.

An efficient method for azidoiodination of alkenes using NaN3/KI/Oxone® combination is described.

A convenient method for the ring opening of epoxides by aromatic amines, catalysed by zirconium sulfophenyl phosphonate in solvent-free conditions, is described.

The hetero-Diels-Alder reaction catalyzed by lanthanum triflate hydrate using diethyl azodicarboxylate as dienophile, yielding differently substituted 1,2,3,6-tetrahydropyridazines, is described.

2,3-Dihydro-1H-1,5 benzodiazepines have been synthetized in very good yield in solvent-free conditions from o-phenylendiamine and ketones in the presence of Yb(OTf)3 as catalyst. The method is applicable to both cyclic or acyclic ketones without significant differences.

A convenient method for the preparation of cyclic ketals and thioketals using zirconium sulfophenyl phosphonate as catalyst is described.

The reaction of phenylselenenyl triflate with diazo compounds is described. Diazoalkanes, α-diazoketones and α-diazoesters gave the corresponding di(phenylselanyl) derivatives either at 0 °C or at room temperature, α-Diazo-β-dicarbonyl compounds gave selectively di(phenylselanyl) derivatives at - 78 °C, while they gave a mixture of di(phenylselanyl)- and mono(phenylselanyl) derivatives either at 0 °C or at room temperature.

A convenient method for the synthesis of 1,2,5-oxadiazole-N-oxides (furoxans) from α-nitro-ketoximes using acidic alumina as catalyst is described.

Layered zirconium hydrogen phosphonate exchanged with the potassium ion was found to be an efficient heterogeneous catalyst for the hydrolysis of sterically hindered phenolic silyl ethers.

A new method for the preparation of N-chloroamides, lactams and carbamates using Oxone® and sodium chloride supported on wet alumina is described.

The Kanematsu transformation was employed for the preparation of tetrahydroisobenzofuran-4-carboxylic acid (12), α-methylation, subsequent conversion into the diazoethanone 14, and, finally, treatment with dirhodium tetraacetate of which furnished the hydrindanone 1 of the steroid C-D ring structure.