The reaction of cyanothioacetamide with diethyl ethoxymethylenemalonate in the presence of triethylamine in hot EtOH proceeds non-selectively and leads to the formation of a mixture of triethylammonium 1,5-diamono-2,4-dicyano-5-thioxopenta-1,3-diene-1-thiolate (minor) and triethylammo-nium 3-cyano-5-ethoxycarbonyl-6-oxo-1Н-pyridine-2-thiolate (major). Upon treatment with primary amines and 37% aqueous HCHO in the boiling aqueous ethanol, the reaction product affords only 4-(1,3,5-thiadiazinan-2-ylidene)-2-(3,4-dihydro-2H-1,3,5-thiadiazin-6-yl)pent-2-enedinitrile derivatives, instead of the expected pyrido[2,1-b][1,3,5]thiadiazines. Triethylammonium 3-cyano-5-ethoxycarbonyl-6-oxo-1Н-pyridine-2-thiolate does not react under these conditions. The structure of the resulted products was confirmed by means of NMR, IR spectroscopy and LCMS. The mechanism of the formation of the products is discussed.

New polyheterocyclic ensembles of 8,9,10,11-tetrahydro-7-thia-1,4,6,8-tetraazabenzo[de]anthracenes were prepared by reaction of easily available 5Н-pyrido[2',3':2,3]thiopyrano[4,5-b]pyridines with Ас2О or acyl chlorides. The starting 5Н-pyrido[2',3':2,3]thiopyrano[4,5-b]pyridines were prepared by reaction of N-methylmorpholinium 4-aryl-3-cyano-6-oxo-1,4,5,6-tetrahydropyridine-2-thiolates with malononitrile dimer.

A general stereoselective approach to previously unknown 1,2,4-triazepane-3-thiones/ones based on reduction or reductive alkylation of readily available 2,4,5,6-tetrahydro-3H-1,2,4-triazepine-3-thiones/ones has been developed. The approach involved treatment of tetrahydrotriazepines with sodium cyanoborohydride in MeOH at pH 3 or with sodium borohydride and excess of carboxylic acid in THF to give 1-unsubstituted or 1-alkyl-substituted 1,2,4-triazepane-3-thiones/ones, respectively. The latter were also prepared by reaction of 1-unsubstituted 1,2,4-triazepane-3-thiones/ones with sodium cyanoborohydride and aldehyde in MeOH in the presence of AcOH.

Palladacycles are an important class of organometallic compounds. They are interesting for their stability and for their important applications as catalysts in cross-coupling reactions. The work described herein relates to the synthesis of a dicyclometallated compound stemming from a diimine ligand, with a doubly metallated aromatic ring. Its reactivity towards a variety of tertiary diphosphines is also considered. The latter ligands show diverse coordination modes, opening the possibility of synthesizing quite different and complex structures bearing transition metal atoms in close proximity to each other.

The preparation of activated carbons has received a great deal of attention in recent years because of the versatility of their properties and the ‘greenness’ of the materials themselves. In the field of chemistry the development of activated carbons has led to the enhancement of numerous catalytic reactions, such as the synthesis of α,β-unsaturated nitriles, chalcones, N-alkylation of imidazoles, and epoxide ring opening reactions.

Acetylation, due to its simplicity, is one of the reactions most frequently used in the chemical and pharmaceutical industry as a method of protecting hydroxyl groups. This is the reason why numerous catalysts have been reported. Many catalysts, despite their usefulness, present some limitations, such as low regioselectivity, high cost, and/or generation of polluting by-products. There is ongoing interest in developing catalysts that are more environmentally benign while keeping a high catalytic activity.

In this work, we have designed, developed, and characterised activated carbons of acid or basic character. These materials have been tested as heterogeneous catalysts in the acetylation reaction of primary and secondary alcohols. The experiments carried out show good catalytic activity, whose magnitude depends on the type of carbon used. This protocol presents several of the characteristics related to the sustainability of chemical processes, such as, the innocuous nature and the affordable cost of the catalytic material, the absence of reaction solvent, and the ease of reaction-medium work-up. Results, experimental details, and the rationalization thereof will be presented in this meeting.

Palladacycles are very versatile compounds and they are known for a good number of ligands. Their main applications are as catalysts, sensors or as antitumor agents. In the particular case of the thiosemicarbazone ligands, these react with palladium salts to give very robust cyclometallated compounds, which present great air and thermal stability; the ligands themselves show a high biological activity. Moreover, when the corresponding thiosemicarbazone is functionalized with a crown-ether moiety, the resulting palladacycle behaves as a new type of sensor.

Once palladated the thiosemicarbazone ligand behaves as tridentate, thus occupying all but one of the coordination positions in the square planar environment of the palladium atom. If the ligand is forced to react in the thione fashion with respect to the sulfur atom, the resulting palladacycle is a mononuclear species with the fourth coordination position readily accessible for further modifications.

In this communication we present the synthesis of [3,4-(C₈H₁₆O₅) C₆H₃C(H)=NN(Me)C(=S)NH₂] (1) and its reactivity towards Li₂PdCl₄ to obtain the mononuclear cyclometallated compound [Pd{3,4-(C₈H₁₆O₅)C₆H₃C(H)=NN(Me)C(=S)NH₂}(Cl)] (1Pd). The characterization of both compounds was carried out using IR and ¹H NMR spectroscopy.

This paper reports the synthesis of two new organotin hydrides containing the (phenyldimethylsilyl)methyl ligand. It was found that the reaction of (phenyldime thylsilyl)methylmagnesium bromide in ether afforded ((phenyldimethylsilyl)methyl) trimethyltin (2) (72%), and with (-)-menthyldimethyltin bromide 3 gave (((phenyl dimethylsilyl)methyl)(1R,2R,5R)-2-isopropyl-5-methylcyclohexyl)dimethyltin (4) (84%). Bromodealkylation of 2 with bromine in MeOH led to the corresponding monobromide 5 (82%), which upon reduction with LiAlH₄ yielded ((phenyldimethyl silyl)methyl)methyltin hydride (6) (95%). The best method for obtaining the corresponding bromostannylated derivative of compound 4, i.e., (((phenyldime thylsilyl)methyl)(1R,2R,5R)-2-isopropyl-5-methylcyclohexyl)methyltin bromide (7) was the exchange reaction between 4 an HgBr₂ that led to 7 with 90% yield. The reduction of bromide 7 with LiAlH₄ gave a diastereomers mixture of (((phenyldime thylsilyl)methyl)(1R,2R,5R)-2-isopropyl-5-methylcyclohexyl)methyltin hydride (8). Some physical properties, and ¹H, ¹³C, and ¹¹⁹Sn NMR of the new organotin hydrides as well as that of their intermediate precursors are included.

This paper reports a study on the free radical hydrostannation of ((4S,4'R,5R,5'S)-2,2,2',2'-tetramethyl-[4,4'-bi(1,3-dioxolane)]-5,5'-diyl)bis(diphenyl methylene) diacrylate (1) and dimethacrylate (2) with triorganotin hydrides, R₃SnH (R = Me, n-Bu, Ph). The preliminary investigations show that these reactions could lead to mixtures of products of cyclohydrostannation and/or mono- or diaddition according to the organotin hydrides employed and the reaction conditions used. The addition of Me₃SnH to 1 afforded a mixture of three organotin compounds from which it was obtained pure the new 13-membered macrodiolide 3 (48%). The other two organotins could not be separated and they probably are products of mono or diaddition. The addition of n-Bu₃SnH to diester 1 led to a mixture of two organotins, the one in major proportion (91%) being the product of diaddition 4. The minor product (9%) could not be isolated pure. The hydrostannation of 1 with Ph₃SnH led to one organotin: the product of diaddition 5. The hydrostannation of the dimethacrylate 2 with the organotin hydrides R₃SnH (R = Me, n-Bu, Ph) under the same reaction conditions, led in the three cases to mixtures containing mainly diaddition products, and no cyclization products being detected. Some physical characteristics of the new compounds including selected values of ¹H, ¹³C, and ¹¹⁹Sn, NMR are included.

Nicotinic acetylcholine receptors (nAChR) are ligand-gated ion channels formed by the assembly of five subunits. Receptor activity could be subjected to both positive and negative modulation at allosteric sites by endogenous neurotransmitters as well as synthetic ligands such as steroids, bivalent cations, alcohols, and a range of drugs. The subtype of α7 nAChR has been considered a potential therapeutic target for Alzheimer’s disease, schizophrenia, and other neurological and psychiatric disorders. In this work, we present the synthesis of a novel series of phosphonate-functionalized 1,4-disubstituted 1,2,3-triazoles with potential activity over α7 AChR.

These compounds were synthesized through the copper-catalyzed Huisgen 1,3-dipolar cycloaddition of organic azides and alkynes. Copper nanoparticles (CuNPs) immobilized on different supports were prepared using the CuCl₂-Li-DTBB reducing system previously reported by our group. In our first studies, we determined that CuNPs over activated carbon were the most efficient catalyst in the reaction between 1-(azidomethyl)naphthalene and propargyl alcohol.

The employment of propargyl alcohol as alkyne allowed us further derivatizations on this triazole in order to obtain a small library of compounds which were tested as positive allosteric modulators (PAMs) of nAChR. We have found that the ones functionalized with phosphonates moieties have shown the desired activity, whereby we decided to extend the family of compounds functionalized with phosphorus moieties.

Hydantoins and their sulfur containing analogues, thiohydantoins, are cyclic ureides that have attracted huge attention ever since their discovery. Most of them are biologically active compounds and several points of structural diversity have made them very synthetically attractive.

Although substituents can be introduced to the hydantoin nucleus, most substituted hydantoins are synthetized from substrates already containing these groups, while forming the hydantoin nucleus. This is a common route to the synthesis of hydantoins and one of them is employed in this study.

A series of 3-allyl-2-thiohydantoins is synthetized from various α-amino acids in a reaction with allyl isothiocyanate. The substitution of the acquired thiohydantoin depends on the structure of the starting α-amino acid. The residual group of the α-amino acid becomes the substituent at the C5-position, while N-monosubstituated amino acids give rise to a subtituent in the N1-position. The reaction is carried out in a two-step process and the reaction conditions generally depend on the nature of the amino acid itself. All thiohydantoins are obtained in a good yield and fully characterized by NMR and IR spectroscopy, as well as X-ray crystallography.