24 New triazenes derived from the 1-alkylpiperazines have been synthesized.Each 1-alkylpiperazine was treated with a diazonium salt solution to produce the new triazenes, which have been characterized by proton and carbon-13 NMR spectroscopy, IR spectroscopy and by mass spectrometric analysis.Assignment of the chemical shifts to specific protons and carbons in the piperazine ring was facilitated by comparison with the chemical shifts in the previously reported 1-methyl-4-[2-aryl-1-diazenyl]piperazines (1).
New perylene monoimides, diimides and bis-diimides have been designed and synthetized.A detailed investigation of the synthesis of these compounds has also been performed in order to highlight the crucial factors for obtaining a specific class of molecules.Specifically, the attention has been focused on the synthesis of the intermediate perylene monoimides which are very useful precursors for many molecules difficult to obtain.Furthemore, two synthetic pathways have been developed for obtaining the bis-diimides variously substituted.These final compounds are predicted to mimic the excellent electron acceptor properties of fullerene derivatives and they can be used as building blocks to form 3D semiconducting materials.
Reactions that convert carbon-hydrogen (C-H) bonds into carbon-carbon (C-C) or carbon-heteroatom (C-Y) bonds are attractive tools for organic chemists, potentially expediting the synthesis of target molecules via functional group interconversion. More explorative studies have shown Complex Induced Proximity Effect (CIPE) to be a solution- provider for the synthesis of bioactive compounds. This might act as excellent pathfinders to new drugs for combating microorganisms' resistance challenges to old existing drug. So, a constant review into CIPE and lithiation chemistry is crucial because they offer excellent pathways to new heterocyclic compounds which are essential agents in drug design and discovery.
The enzyme sirtuin 1 (SIRT1) is a major target for the treatment of various metabolic disorders.Herein, a practical synthesis of imidazo[1,2-b]thiazole derivatives, one of the most comprehensively studied class of synthetic SIRT1 activators, is presented.The synthesized SIRT1 activators, the in vitro-identified metabolite of SRT1720, and the eightfold deuterated analytical standards were obtained through a six-step protocol yielding model compounds with a conserved core structure and two variable moieties.A multiplicity of potential SIRT1 activators and metabolites can be prepared with substituents enabling the modification of biological effects.
Chemical fixation of CO2 to value-added products/materials/fuel has attracted more and more attention from both academia and governmental agencies all over the worldsince CO2 is an easily available and sustainable C1 resource with the advantage of being abundant, nontoxic, nonflammable and renewable. Synthesis of organic carbonates starting from CO2 is one of the most promising methodologies and has been widely investigated. The use of CO2 and 1,2-diols can bring many advantages, such as reusing the byproducts generated in the industrial dimethyl carbonate (DMC) process and simplifying the post purification process. In this paper, synthetic methods with reaction mechanism of ethylene carbonate (EC), propylene carbonate (PC) and glycerol carbonate from CO2 and ethylene glycol (EG), or propylene glycol (PG) or glycerol are systematically discussed.
New and convenient one-pot syntheses of 2-substituted aryl (indolyl) kojyl thioether from 2-substituted aryl (indolyl) kojic acids have been found.Firstly, the 2-substituted aryl (indolyl) kojic acids were readily obtained from coupling of aldehyde, kojic acid and indoles in the presence of p-toluenesulfonic acid as catalyst in good yields and with high selectivity.Then, 2-substituted aryl (indolyl) kojic acids were reacted with thionyl chloride to afford corresponding 2substituted aryl (indolyl) kojic chlorides.Finally, the 2-substituted aryl (indolyl) kojic chloride derivatives were reacted with benzenethiols in presence of triethylamine in t etrahydrofurane to afford the corresponding thioether derivatives in good yields.
Purification of synthetic oligodeoxynucleotides (ODNs) is simply achieved by capping failure sequences with a polymerizable phosphoramidite followed by polymerization.In this article, the reduction of the amount of polymerization monomer to drastically increase ODN extraction efficiency, the use of a centrifugal filterunit to ease the extraction process and the notification of using fresh phosphoramidite solutions are described.In addition, further evidence to support the purity of ODN and discussions of ODN stability under radical polymerization conditions are provided.
A series of mono protected ,-diamines protected with photolabile carbamates has been synthesized by reac- tion between the corresponding ,-diamines and either o-nitrobenzyl or 1-(2-nitrophenyl)ethyl phenyl carbonate.
An highly expeditious synthetic approach for the synthesis of benzenemethanesulfonamides (1a-k) and their new corresponding N,N-diethyl substituted amido moieties (2a-k) has been achieved in aqueous medium at room temperature.The reaction condition was thoroughly optimized thereby allowing significant rate enhancement and resulting into excellent yields.The chemical structures of the successful candidates were confirmed using elemental analytical and spectroscopic data such as IR, 1 H NMR, 13 C NMR and some selected mass spectral data.
Palladium catalysis is an efficient way to obtain trimethylsilyl substituted benzopyran derivatives.After screening a series of reactions , we found optimized conditions.
Several novel palladium triphosphine complexes have been synthesized and tested as recyclable catalysts for the methoxylation of alkynes into acetals in ionic liquids. A complete conversion of phenylacetylene was achieved with only 0.2% of (Pd(Triphos)NCMe)((PF6)2) in a methanol/(BMIM)(BF4) mixture. We discovered that the addition of an ionic liquid to methanol allowed not only to increase the activity of the palladium catalyst but also to provide a recyclable catalyst which can be reused several times with a weaker drop of activity. To complete these catalytic studies, we describe the synthesis of the first poor -electron-donating/strong -electron-acceptor linear Triphosphine which, after palladium coordination, led to a better selectivity compared to its Triphos analogue. The performances of recovered ionic liquid re- action mixtures show for the first time that P-tridentate ligands efficiently immobilize palladium catalysts and lead to se- lective catalytic systems benign for environment.
We describe the preparation and use of two new imidazolium-bound Rose Bengal derivatives for singlet oxygen generation.Photolysis of oxygen-saturated solution of furan rings in the presence of the imidazolium-bound sensitizers provides the corresponding butenolides.The sensitizers could be recovered after the oxidation reaction.
The synthesis of various substituted Biginelli 3,4-dihydropyrimidinone/thione and Hantzsch 1,4- dihydropyridine derivatives has been achieved using a modified procedure in the presence of potassium ter-butoxide (t- BuOK) as a catalyst under solvent-free conditions, in good to excellent yields.
The use of benzoyl, isobutyryl and dimethylaminomethylidene groups for the protection of the exocyclic amino function of 2-aminopurine during oligonucleotide synthesis has been investigated.Best results in the synthesis were obtained with the monomers of 2-aminopurine protected with the isobutyryl group.
Coronoids with holes shaped like an odd carbon benzenoid have antiaromatic holes and antiaromatic conjugated circuits.Another class of concealed diradical coronoids has been identified.They are Hückel molecular orbital diradicals (HOMO = LUMO = 0, each with a single electron occupancy) that have VB (valence-bond) structures (K 0).This new class of concealed diradical coronoids have more enhanced antiaromatic contributions.The smallest holes in graphenes are spin polarized and have antiaromatic characteristics.
This review discusses from a qualitative viewpoint three-dimensional structures (hydrocarbons and carbon allo- tropes) that can be obtained from the 4,6,12-archimedean tiling of the Euclidean plane (graphenylene net) or that are re- lated to subgraphs derived from the graphenylene net, insisting on helical structures called (n)heliphenes with alternating 4- and 6-membered conjugated rings. Analogies with benzenoid (n)helicenes allow proposals for non-planar heliphene- related structures that have yet to be explored.
Structures and stability of an extended series of bipyramidal, sandwich and sandwich-bipyramidal mixed complexes formed by conjugated cyclic hydrocarbons (CH) n with s-(Li, Na, K, Be, Mg, Ca) and d-(Cr, Mn, Fe) metals have been studied using DFT B3LYP/6-311+G(df,p) calculations.Stable structures of the compounds satisfy a general (6n + 6d + 12c) electron-count rule, where n stands for total number of the basal hydrocarbon rings, d is total number of d-metal centers (or separate sandwich moieties) and is total number of apical metal-carbonyl groups.It is shown that stabilization of the studied polyhedral organometallic structures (induced aromaticity) is caused by filling 6 -electronic shells of basal (4-6)-membered cycles provided by donation of additional electrons from metal centers thereby acquiring closed 18electron shells.
Clar's aromatic sextet theory provides a good means to describe the aromaticity of benzenoid hydrocarbons, which was mainly based on experimental observations.Clar defined sextet pattern and Clar number of benzenoid hydrocarbons, and he observed that for isomeric benzenoid hydrocarbons, when Clar number increases the absorption bands shift to shorter wavelength, and the stability of these isomers also increases.Motivated by Clar's aromatic sextet theory, three types of polynomials (sextet polynomial, Clar polynomial, and Clar covering polynomial) were defined, and Randic´'s conjugated circuit model was also established.In this survey we attempt to review some advances on Clar's aromatic sextet theory and Randic´'s conjugated circuit model in the past two decades.New applications of these polynomials to fullerenes, and calculation methods of linear independent and minimal conjugated circuit polynomials of benzenoid hydrocarbons are also presented.
We discuss the results of selected projects where we estimate the strength of aromatic stabilization with the help of the Energy Decomposition Analysis within the Density Functional Theory framework.The paper introduces a new methodology to quantify the relative strength of aromaticity in aromatic and antiaromatic organic compounds.The approach is also useful for the study of homo(anti)aromatic systems and for compounds where the traditional methods do not give a consistent answer concerning their aromatic character such as small-ring compounds and metallabenzenes.
