Current Organic Synthesis - Volume 14, Issue 7, 2017

Background: Xanthenes are a class natural and synthetic heterocyclic compounds that exhibit a broad spectrum of biological and synthetic applications. The readership of this review paper will consist of chemists involved with organic chemistry, synthetic organic chemists, pharmacists and biochemists. Objective: This review aims to present an overview of the chemical aspects of low molecular weight xanthenes and their chemical synthesis by cycloaddition in the search for bioactive species, new catalysts and other applications. Method: We have comprehensively and critically discussed all the information available in the literature concerning the synthesis and reactivity of this molecules. Results: This manuscript presents an overview about the chemical aspects of low molecular weight xanthenes and its chemical synthesis by cycloaddition in the search for bioactive species, new catalyst and other applications. Conclusion: In summary, xanthenes are a class very explored because the broad spectrum of biological properties as previously mentioned. Due this fact, synthetic strategies for obtain this system have been explored with general success with two or three component, and for instance, with benzyne intermediates. It's possible react a 1,3-dicarbobyl compound such as lawsone, dimedone, Meldrum acid, coumarin, phenols and naphthols with different aldehydes.

Background: The Diels-Alder reaction has played a fundamental role in advancing synthetic chemistry over the years and continues to greatly impact modern synthetic methodology. Ever increasing interest in the application of ionic liquids (ILs) as catalyst and solvents in organic synthesis has provided the impetus to explore their application in Diels-Alder chemistry with the goal to improve efficiency as well as chemo-, regio- and enantio-selectivity. Objective: The review focuses on recent progress in the area of IL-mediated Diels-Alder reactions through illustrative examples that demonstrate their efficacy as solvent and catalysts. Conclusion: It is clear from the review of the topic that a vast amount of work has been done in this area, employing diverse types of ILs which were employed either alone or in conjunction with Lewis-acids, metal ions, chiral additives, organocatalysts, and/or other additives. The results in comparison to conventional solvents have demonstrated improved yields, faster rates, as well as improved regio- and enantioselectivity. These attributes along with the advantages associated with recycling/reuse clearly point to ILs as superior media for Diels-Alder chemistry. Much of the emphasis has been on synthesis but some fundamental mechanistic work aimed at understanding rate enhancement and endo-selectivity have also been reported.

Background: Chemists have been interested in light as an energy source to induce chemical reactions since the beginning of scientific chemistry. The organic photochemical reactions do not require toxic or polluting reagents so these reactions presented perspectives in the context of green chemistry and sustainable processes. Objective: The largest classical divisions of organic chemistry are constituted by heterocycles. The role of heterocyclic compounds in a number of areas cannot be ignored. That's why the chemists are continuously trying to design and synthesize heterocycles. This review summarizes the chemistry of photochemical reactions with emphasis on their synthetic applications. In this review, the most important photochemical transformations that have been employed in six-membered N-heterocycles synthesis are presented. Conclusion: This review discussed the research activities in organic photochemistry that are applicable in organic synthesis. This review outlined the synthesis of heterocyclic compounds. Traditional approaches require highly specialized or expensive equipment, are highly inconvenient, or would be of limited use to the synthetic organic chemist. Therefore, these have been omitted by them. Photochemistry can be used to prepare a number of heterocycles selectively, efficiently and in high yield.

Background: In 1996, the Nobel Prize in Chemistry was awarded jointly to Robert F. Curl Jr., Sir Harold W. Kroto, and Richard E. Smalley for their discovery of fullerenes. This ignited the research enthusiasm on the fullerene and lasted for two decades. However, reactions for modifying the surface of fullerene were not summarized completely although a great deal of fullerene derivatives had already been synthesized via the modification on the fullerene. Objective: Presented herein was an overview on reactions that were able to bridge other structural moieties onto the surface of the fullerene. Conclusion: In principle, [1+2], [2+2], [3+2], and [4+2] cycloaddition together with oxidative nucleophilic addition functioned as the promising reactions for modifying the fullerene. The methylene in malonic acid, the nitrogen atom in azide as well as other methods for producing carbene provided the single atom (expressed by “1”) for the [1+2] cycloaddition (the “2” represented the C=C in the fullerene). The strategies for generating azomethine ylide as the 1,3-dipole (expressed by “3”) were able to furnish a five-membered nitrogen-fused heterocycle onto the fullerene via the [3+2] cycloaddition, while 1,3-dienes (expressed by “4”) were capable of appending a six-membered ring onto the fullerene via the [4+2] cycloaddition, which was also called Diels- Alder reaction for opening the surface of the fullerene. Finally, the nucleophilic additions of organolithium and Grignard reagent were performed on the fullerene. As a result, some potential nucleophiles such as hydroxyl and amino groups were bridged with fullerene by a single bond. Although a large number of fullerene derivatives were prepared, the synthetic protocols were still limited within the aforementioned reactions.

Background: Metathesis reactions represent an attractive and powerful tool for the synthesis of new carbon-carbon double bonds. The development of ruthenium complexes allows to perform the transformation in both organic and polymer chemistry. Indenylidene catalysts constitute a very important part of this area, as they have been found to be resistant to harsh reaction conditions (temperature and presence of functional groups). In addition, thanks to their good catalytic activities they quickly became a mainstream catalysts in metathesis-type reactions in recent years. Objective: In this Review we intend to give a general overview of indenylidene catalysts in a broad sense. Conclusion: Synthesis and activity studies of modified first- and second-generation complexes as well as catalysts bearing pyridine or bidenate ligands are described herein. The application of indenylidene catalysts is discussed in light of both simple model reactions and synthesis of biologically active compounds.

Aim and Objective: Chromenes are one of the most demanded compounds that are recognized for their unique pharmacological and biological activities. This report illustrates the synthesis of new chromene series and chromene based azo chromophores as first example and examines their biological applications in order to explore their possible biological and cytotoxic activities. Material and Method: Using multicomponent methodology, two new families of 4H-chromene and chromene azo chromophores have been successfully synthesized. These compounds were evaluated for their antimicrobial activity as well as their cytotoxicity against three cancer cell lines. The docking simulations were performed for their structure-activity relationship analyses. Results: Novel chromene and chromene azo chromophores have been synthesized successfully using multicomponent methodology. Several of these compounds showed significant potent antimicrobial activities compared to reference drugs. In addition, antiproliferative analysis against three target cell lines was examined. Compounds 4a, 4b, 4c, and 7c possessed significant antiproliferative activity with an IC50 of 0.3 to 2 μg/mL, while their docking study proved that the pharmacophore features played a crucial role in reducing the regulation of cancer cell signaling or apoptotic activation. Conclusion: New derivatives of benzo chromene were obtained via multicomponent methodology. The new compounds were examined for their antimicrobial and antiproliferative activities. Molecular docking study was carried out to clarify the structural desires and target binding properties as a trial for explaining the structureactivity relationship profile

Background: Hydrazonoyl halides are useful for the synthesis of several heterocyclic derivatives. Thiadiazoles are a significant category of heterocyclic organic compounds with comprehensive range of biological accomplishments. Method: New bisthiadiazoles were prepared by the reaction of hydrazonoyl derivatives with methyl-2- arylidene hydrazinecarbodithioates in dioxane and in the presence of triethylamine. The synthetic method involves nucleophilic substitution reactions via intramolecular cyclization reactions followed by evolving methanethiol gas. The new synthesized compounds were identified by elemental analysis and various spectral data. The antioxidant strength of the synthesized thiadiazoles was explored, utilizing different established in vitro methods, such as DPPH, superoxide dismutase –like and ABTS scavenging activities. Results: The antioxidant activities of the synthesized thiadiazoles were apparent as it presented significant reducing power, superoxide dismutase like ability, ABTS and DPPH-scavenging activities. Furthermore, the antimicrobial activities and the MIC values of the new thiadiazoles were evaluated against both Gram-negative and Gram-positive microorganisms. The thiadiazoles 4a, 4b and 4d displayed a substantial nuclease like activities on the chromosomal DNA. Conclusion: In the present work, we synthesized a novel series of bisthiadiazole derivatives. Thiadiazoles were verified for their antimicrobial efficiency against various bacterial strains. In addition, the antioxidant activates for these compounds to scavenge free radicles were examined using DPPH, ABTS and SOD- like activities. DNA binding and degradation efficiency for these compounds were examined.

Background: pyrazolo[3',4':4,5]pyrimido[1,6-b][1,2,4]-triazines have been found to possess a wide range of medical activities. Objective: we interested to synthesis a new series of pyrazolo[3',4':4,5]pyrimido[1,6-b][1,2,4]triazines via the reaction of 1,3-diphenyl-4-hydrazino-pyrazolo[3,4-d]pyrimidine with ethyl aroyl pyrovates and invistigate thier antimicrobial activity. Not only the biological activity is our aim but also, to elucidate the actual tautomeric structure of the products. Method: A new series of pyrazolo[3',4':4,5]pyrimido[1,6-b][1,2,4]triazine derivatives was prepared via condensation of ethyl aroylpyruvates with 1,3-diphenyl-4-hydrazino-pyrazolo[3,4-d]pyrimidine. Also, treatment of these compounds with hydrazine hydrate afforded a new series of 1,3-diphenyl-4-(7-aryl-2,6-dihydropyridazino[ 3,4-e][1,2,4]triazin-3-yl)-1H-pyrazol-5-amine. Results: The mechanism of the reaction was discussed and proved to proceed via Dimroth rearrangement. The structure of all the newly synthesized compounds was established on the basis of spectral data and elemental analysis. The antimicrobial activity of the products was screened and some derivatives showed promising activities against the used bacteria and fungi species. Conclusion: We success in synthesis of a new series of bioactive pyrazolo[3',4':4,5]pyrimido[1,6-b][1,2,4]triazines and elucidation of their actual structure.

Aim and Objective: Amides are a very important class of organic compounds. As a type of important amides, arylacetamides have gained considerable attention since their pharmacological and biological activities. Therefore, the development of new methods for the synthesis of aryl acetamides is of significant interest among organic chemists. Material and Method: Using N-methoxymethyl-N-methylcarbamoyl(trimethyl)silane as a secondary amide source, the aminocarbonylation of benzylic chlorides by palladium-catalyzed afforded the corresponding protected secondary arylacetamides in good yields under mild reaction conditions. The methoxymethyl group was used as an amino protecting group and can be easily hydrolyzed in acid condition to afford secondary arylacetamides. Results: A novel and highly efficient synthetic method toward secondary arylacetamides by palladium– catalyzed aminocarbonylation of aryl halides was developed using N-methoxymethyl-N-methylcarbamoyl(trimethyl) silane as secondary arylacetamides source, and investigated the scope and limitation of the aminocarbonylation. The relative position of substituent on the aryl ring to influence on this transformation. In this protocol, the methoxymethyl group was used as an amino protecting group and can be easily hydrolyzed. Conclusion: We have investigated the scope and limitation of the aminocarbonylation of benzylic chlorides with carbamoylsilane, expanded to synthesis of secondary arylacetamides using N-methoxymethyl-Nmethylcarbamoyl( trimethyl)silane as a secondary amide source.