Synthetic Work Research Articles

Recent advances in the total synthesis of vinigrol

(−)-Vinigrol, a unique, novel, and biologically significant diterpenoid, was isolated from fungal strain Virgaria nigra F-5408 in 1987 by Ando and co-workers. Initial biological studies found that vinigrol possesses both antihypertensive and platelet aggregation-inhibitory properties. More recent studies have identified vinigrol as a tumor necrosis factor (TNF) antagonist. In addition, vinigrol has also been shown to be effective in the treatment of human immunodeficiency virus (HIV) and inflammation. Structurally, the 1,5-butanodecahydronaphthalene core with eight contiguous stereocenters located in vinigrol represents the unprecedented and unique motif found in natural product small molecules. This promising biological activities of vinigrol combined with its unique terpene framework have attracted significant attention from the synthetic community. However, the total synthesis of vinigrol has been regarded as one of the most challenging tasks in the synthesis community for more than two decades. Numerous research efforts have been oriented toward the total synthesis of vinigrol, including Paquette, Corey, Hanna and other groups before 2008. Until now, four elegant total syntheses have been reported. In 2009, Baran and co-workers completed the first total synthesis of (±)-vinigrol, and the challenging 1,5-butanodecahydronaphthalene core was constructed by a way of intermolecular Diels-Alder and intramolecular Diels-Alder reactions followed by Grob fragmentation. Key salient features including an unusual dipolar cycloaddition for establishing the cis -orientation of the C8-methyl and C8a-hydroxy groups, and a later stage of Shapiro reaction via the tri-anionic species to deliver the final target. The synthesis was completed in a 23-step route with 3% overall yield from commercially available materials. This work represented a landmark achievement in the vinigrol synthesis. In 2013, Njardarson and co-workers completed another remarkable total synthesis of (±)-vinigrol, and the challenging 1,5-butanodecahydronaphthalene core was established with an elegant oxidative dearomatization/intramolecular Diels-Alder reaction followed by a Wharton fragmentation. In 2019, Luo and co-workers reported the first asymmetric total synthesis of (−)-vinigrol, with an impressive transannular Diels-Alder reaction as the key step. This scalable synthesis of (−)-vinigrol was completed in a 20-step route with 1.4% overall yield from commercially available materials, and provided over 600 mg of natural product in one operation. It should be noted that the Diels-Alder reaction was a crucial element in the synthetic strategy toward vinigrol in all these noteworthy achievements. Later, our group reported another asymmetric total synthesis of (−)-vinigrol using a unique Type II [5+2] cycloaddition and a novel ring contraction cascade as the key reactions. This synthetic work represents the first example of an intramolecular [5+2] cycloaddition to construct eight-membered ring system in natural product synthesis. Furthermore, the linear sequence of our concise asymmetric total synthesis of (−)-vinigrol was only 14 steps from commercially available material and without the need for protecting groups during the whole synthesis. The goal of this review is to provide a survey of advances in the total synthesis of vinigrol and discuss the synthetic strategies and tactics in each synthesis. The authors also hope that this review will serve a useful guidance for organic chemists who involved in total synthesis of natural products and provide a stimulus for inventions and further advances in this exciting area.

University students’ perception of the factors affecting preschool and primary students’ recycling behaviour as a tool to improve environmental education in the university curriculum (Percepción de los estudiantes universitarios de los factores que influyen sobre la conducta de reciclaje de los estudiantes de educación infantil y primaria como herramienta para mejorar la educación ambiental en el currículum universitario)

ABSTRACT The purpose of this synthetic work is to examine university students’ perception of children’s relevant factors for recycling behaviour aiming to improve their university curriculum. The main idea of this analysis was to focus on faculty of education students, as they will be the future environmental educators that will provide the basic environmental knowledge to students in preschool and primary education. A systematic review was performed to reveal potential factors influencing the recycling behaviour of children, and then a new survey was conducted through a questionnaire to evaluate the 320 university students’ perception of the Faculty of Education of Aristotle University of Thessaloniki on the factors affecting the preschool and primary school students towards recycling. The findings indicated that university students’ perception is in line with the bibliography and show that according to students, the family environment is the most important factor affecting children’s recycling behaviour.

Identifying effective restoration approaches to maximize plant establishment in California grasslands through ameta‐analysis

One reason restoration often fails is a lack of native plant establishment. Establishment failure can occur due to a lack of dispersal into the site, inappropriate abiotic conditions for plant survival, or biotic interactions that reduce germination rates or seedling survival. Understanding what is limiting establishment is critical for restoration success. Unfortunately, there has been little synthetic work to identify which restoration practices (e.g., direct seeding, weeding, irrigation) are most likely to improve plant establishment. Here we used a meta‐analytical approach to determine what practices are most likely to enhance establishment success in grassland communities in California. We explored the impact of these practices on whole communities as well as on different functional groups (grass and forb). We categorized techniques by the constraint they addressed (dispersal, abiotic, or biotic) to determine which restoration practices are more likely to improve plant establishment. We found that addressing the dispersal filter is the best way to improve plant establishment regardless of the functional group. This suggests that most native plants targeted in restoration are seed limited. While we were able to identify restoration techniques that improve plant establishment, our synthesis revealed that there were insufficient numbers of studies and a lack of uniformity between treatments that hampered efforts to make broad conclusions. If we can expand research to more ecosystems, and use standardized treatments within each ecosystem, the restoration community could synthesize research more efficiently, which would inform our ultimate goal of increasing the success of restoration.

Asymmetric Total Synthesis and Biosynthetic Implications of Perovskones, Hydrangenone, and Hydrangenone B.

Perovskones and hydrangenones are a family of structurally complex triterpenoids that were mainly isolated from the genus Salvia medicinal plants. These isoprenoids exhibit a broad range of biological activities, such as antitumor and antiplasmodial activities. Here, we report the collective total synthesis of perovskone, perovskones C, D, F, hydrangenone, and hydrangenone B. The key strategies in this work include the following: (1) an asymmetric photoenolization/Diels-Alder reaction was developed to construct a tricyclic ring bearing three contiguous quaternary centers, which was used to build the core icetexane skeleton; (2) a bioinspired Diels-Alder reaction of perovskatone D with trans-α-ocimene was applied to stereospecifically generate perovskones; (3) late-stage oxidations and ring forming steps were developed to synthesize perovskones and hydrangenones. Our synthetic work suggests that (1) perovskatone D may serve as the precursor of the biosynthesis of perovskones and (2) the formation of hydrangenone and hydrangenone B, containing a five-membered D ring, may involve an oxidative ring cleavage and ring regeneration process.

Quest for a Cure: Potential Small-Molecule Treatments for COVID-19, Part 2.

During the first year of the outbreak of the COVID-19 pandemic, many drugs and drug candidates have been evaluated as treatment options. None yet has proved to be an effective cure, but progress in controlling the disease has been made. In June 2020 we published an article that described the mechanistic rationale behind the repurposing of seven licensed drugs in clinical trials for the treatment of COVID-19 and reviewed synthetic routes to these drugs. Several developments have occurred since then. Remdesivir (trade name Veklury) has been approved for use in the U.S. and Europe. Dexamethasone, a steroid drug first approved in 1959, has shown mortality reduction in severe COVID patients. Molnupiravir, a new and promising oral antiviral drug, is being studied in late-stage clinical trials. In this review, we update synthetic work that has been recently published on remdesivir, provide an overview of several routes to molnupiravir, and review classical routes to dexamethasone as well as some of those more recently developed.

Mediterranean vector Soviet foreign trade in the 1920s

The purpose of the article is to clarify the features of Soviet foreign trade in the Mediterranean basin in the 1920s. The relevance of the study is due to the fact that the Mediterranean Soviet foreign trade of the period of the new economic policy has never actually been a separate scientific and historical problem. Methods of research: chronological, historical-comparative, descriptive. The main results: established a list of Mediterranean countries with which the Soviet state maintained trade relations during the period of the new economic policy; clarified the commodity and raw materials nomenclature of export-import operations in the Mediterranean zone; it was established that one of the main reasons for the establishment by Western countries of trade relations with the Bolshevik state was the economic crisis of 1920-1921, which swept the West; At the end of the study period, the Soviet government used the Great Depression to exert economic pressure on Western countries; disclosed the dynamics of Soviet trade at that time in the southern direction; revealed the dependence of Soviet foreign trade on the political environment; analyzed the Ukrainian component of the Soviet Mediterranean trade of the 1920s, using the example of the southern direction of Soviet foreign trade, it is shown how Moscow gradually limited the economic independence of the Ukrainian SSR until its complete leveling. Practical significance: the results of the study can be recommended for use in synthetic works on the history of Ukraine, the USSR, foreign trade and international relations of the 1920s, the development of relevant academic disciplines and special courses. These materials can also be used to promote historical knowledge. Originality: the article is, in general, original, it was made taking into account the developments of domestic and foreign researchers, with the involvement of a significant array of documents from a number of Ukrainian and Russian archives. Scientific novelty: for the first time in domestic historiography the peculiarities of the Soviet foreign trade of the 1920s in the Mediterranean basin are characterized, and also the role in the corresponding processes of the Ukrainian SSR is. The scientific novelty of the work is also due to the introduction into scientific circulation of a significant complex of archival materials, primarily documents of various services and structures of the People's Commissariat for Foreign Trade of the RSFSR, the Ukrainian SSR and the USSR. Type of article: overview.

Synthesis and structural elucidation of a series of isoflavones-based on FPR antagonists

Synthesis and structural elucidation of a series of isoflavones-based on FPR antagonists

Isoselenocyanates: Synthesis and Their Use for Preparing Selenium-Based Heterocycles

AbstractIsoselenocyanates (ISCs) are a class of organoselenium compounds that have been recognized as potential chemotherapeutic and chemopreventative agents against cancer(s) and infectious diseases. ISC compounds are chemically analogous to their isosteric relatives, isothiocyanates (ITCs); however, they possess increased biological activity, such as enhanced cytotoxicity against cancer cells. ISCs not only serve as significant products, but also as precursors and essential intermediates for a variety of organoselenium compounds, such as selenium-containing heterocycles, which are biologically active. While syntheses of ISCs have become less difficult to accomplish, the syntheses of selenium-containing heterocycles are often difficult due to the use of highly toxic selenium reagents. Because of this, ISCs can serve as versatile reagents for the preparation of these heterocycles. In this review, the classical and recent syntheses of ISCs will be discussed, along with notable and recent synthetic work employing ISCs to access novel selenium-containing heterocycles.1 Introduction1.1 Selenium and Health2 Isoselenocyanates2.1 Preparation of Isoselenocyanates3 Selenium-Containing Heterocycles3.1 Notable Synthetic Work3.2 Recent Synthetic Work3.2.1 Synthesis of N-(3-Methyl-4-phenyl-3H-selenazol-2-ylidene)benzamide­ Derivatives3.2.2 Synthesis and X-ray Studies of Diverse Selenourea Derivatives3.2.3 Synthesis of Heteroarene-Fused [1,2,4]Thiadiazoles/Selenadiazoles via Iodine-Promoted [3+2] Oxidative Cyclization3.2.4 2-Amino-1,3-selenazole Derivatives via Base-Promoted Multicomponent Reactions4 Conclusion

A Review on Metabolites from Onchidium Genus: Chemistry and Bioactivity.

The Onchidium genus (Mollusca, Gastropoda, Pulmonata, Systellommatophora, Onchidiidae family) is used as the important economical shellfish, due to the high nutritional value and medicinal value. Research over the previous decades indicated that Onchidium sp. mainly contains polypropionates, depsipeptides, terpenoids and other chemical components. Many biological activities of Onchidium (e. g., cytotoxic activities against tumor cells, anti-viral and anti-bacterial activities) have been reported. This review reports a total of 60 compounds, synthetic work and biological studies on Onchidium genus, covering the literature from 1978 to date, with a view to providing a reference and helping for the in-depth research of this genus.

1-Aminobicyclo[2.2.2]octane-2-carboxylic Acid and Derivatives As Chiral Constrained Bridged Scaffolds for Foldamers and Chiral Catalysts

The improvement of molecular diversity is one of the major concerns of chemists since the continuous development of original synthetic molecules provides unique scaffolds usable in organic and bioorganic chemistry. The challenge is to develop versatile platforms with highly controlled chemical three-dimensional space thanks to controlled chirality and conformational restraints. In this respect, cyclic β-amino acids are of great interest with applications in various fields of chemistry. In addition to their intrinsic biological properties, they are important precursors for the synthesis of new generations of bioactive compounds such as antibiotics, enzyme inhibitors, and antitumor agents. They have also been involved in asymmetric synthesis as efficient organo-catalysts in their free form and as derivatives. Finally, constrained cyclic β-amino acids have been incorporated into oligomers to successfully stabilize original structures in foldamer science with recent successes in health, material science, and catalysis. Over the last ∼10 years, we focused on bicyclic β-amino acids possessing a bicyclo[2.2.2]octane structure. This latter is a structural key element in numerous families of biologically active natural and synthetic products and is an interesting template for asymmetric synthesis. Nonetheless, reported studies on bicyclic carbo-bridged compounds are rather limited compared to those on bicyclic-fused and heterobridged derivatives. In this Account, we particularly focused on the synthesis and applications of the 1-aminobicyclo[2.2.2]octane-2-carboxylic acid, named, ABOC, and its derivatives. This highly constrained bicyclic β-amino acid, with a sterically hindered bridgehead primary amine and an endocyclic chiral center, displays drastically reduced conformational freedom. In addition, its high bulkiness strongly impacts the spatial orientation of the appended functionalities and the conformation of adjacent building blocks. Thus, we have first expanded a fundamental synthetic work by a wide ranging study in the field of foldamers, in the design of various stable peptide/peptidomimetic helical structures incorporating the ABOC residue (11/9-, 18/16-, 12/14/14-, and 12/10-helices). In addition, such bicyclic residue was fully compatible with and stabilized the canonical oligourea helix, whereas very few cyclic β-amino acids have been incorporated into oligoureas. In addition, we have pursued with the synthesis of some ABOC derivatives, in particular the 1,2-diaminobicyclo[2.2.2]octane chiral diamine, named DABO, and its investigation in chiral catalytic systems. Covalent organo-catalysis of the aldol reaction using ABOC-containing tripeptide catalysts provided a range of aldol products with high enantioselectivity. Moreover, the double reductive condensation of DABO with various aldehydes allowed the building of new chiral ligands that proved their efficiency in the copper-catalyzed asymmetric Henry reaction.

Newest Born of Nations: European Nationalist Movements and the Making of the Confederacy by Ann L. Tucker

Reviewed by: Newest Born of Nations: European Nationalist Movements and the Making of the Confederacy by Ann L. Tucker Brian Schoen (bio) Newest Born of Nations: European Nationalist Movements and the Making of the Confederacy. By Ann L. Tucker. (Charlottesville: University of Virginia Press, 2020. Pp. 272. Cloth, $45.00.) Antebellum white southerners were not the naval gazers previous generations thought them to be. They looked across the Atlantic and perceived themselves in relational and comparative ways. They proved particularly effective at spinning strands of international news and global ideas into webs of self-justification. Ann Tucker’s Newest Born of Nations offers probably the most probative treatment of how “elite white southerners used an international perspective [or at least a Eurocentric one] to understand, imagine, and defend their visions of nationhood” (4). For Tucker, this operated at a couple of levels. Events from unrealized nationalist efforts in Ireland and Hungary to eventually realized ones on the Italian peninsula offered reference points for considering and intensifying the sectional conflict. Southern sectionalists, for example, invoked and debated images of themselves as a Poland to the Tsarist-like North. Global events also “deepened” southerners’ sense of nationalism, as they looked for metaphors, foils, and models for their own efforts to construct [End Page 422] an independent nation (24). Tucker argues that a wider perspective served as a “mechanism for translating their concerns . . . into the more internationally resonant language of rights, values, and nationhood” (4). In short, white southerners learned to be, or at least talk, like a nation by watching and reflecting on the world around them and their place within it. Those mental efforts did not, however, bring agreement. Tucker identifies three oft-competing strains of southern nationalist thought. A “liberal nationalist”–turned–”liberal secessionist” vein tapped into the rights-based language of the American Revolution, which had been reanimated and romanticized amid the European revolutions of 1848. Southerners celebrated, for example, Italian revolutionary Giuseppe Garibaldi and the European republicanism he symbolically led. This strand, especially prominent in Democratic circles, emphasized that the South had a right to greater self-determination. Aided by voices like exiled Irish nationalist editor John Mitchel, it cloaked “concerns about slavery within broader liberal principles” (114). A second variant that emerged from the embers of the 1848 revolutions was a “conservative nationalism” that, though also generally republican, emphasized the need for authority and law and order. In its balder versions, this strand of thought affixed the South as a bulwark against European-style radical “red republicanism” that many southern whites feared was being imported into the United States. Slavery was trumpeted as a tonic to the perceived excesses of free labor and excessive democracy. This conservative nationalism translated into a call for secession as the best means to defend southern society. In total, Tucker shows that thinking about European political changes taught southern whites to perceive themselves as different from the North. Overlapping southern liberalist and conservative impulses converged in a secessionist impulse that erupted in 1860. Revealing the necessarily slippery use of these labels, Tucker suggests that “it is more appropriate to refer to secessionists who used a liberal versus a conservative perspective, rather than referring to southern liberals versus southern conservatives” (118). It was not uncommon, it seems, for the same person or newspaper to invoke both liberal and conservative justifications. Yet there does emerge a clear trajectory of the emphasis within wartime Confederate global thinking. Early on, Jefferson Davis’s government appealed to liberal nationalist impulses that had helped free parts of Italy from Hapsburg rule and ultimately led to its unification under a constitutional monarchy. Yet for reasons not fully explored here, but presumably tied to slavery, those liberal nationalist arguments had little impact. Their failure forced Confederate propagandists to turn toward conservative [End Page 423] arguments they hoped would land with Hapsburg rulers and conservative Catholics, a point that reinforces the argument of Don Doyle’s synthetic work The Cause of All Nations: An International History of the American Civil War (2014). In seizing on the global roots of Confederate nationalism, Tucker builds on ground previously trod by Andre Fleche, Paul Quigley, Timothy Roberts, and Niels Eichhorn. But Tucker adds to...

Recent progress on pristine two-dimensional metal-organic frameworks as active components in supercapacitors.

Two-dimensional (2D) metal-organic frameworks (MOFs) are a new generation of 2D materials that can provide uniform active sites and unique open channels as well as excellent catalytic abilities, interesting magnetic properties, and reasonable electrical conductivities. Thus, these MOFs are uniquely qualified for use in applications in energy-related fields or portable devices because they possess fast charge and discharge ability, high power density, and ultralong cycle life factors. There has been worldwide research interest in 2D conducting MOFs, and numerous techniques and strategies have been developed to synthesize these MOFs and their derivatives. Thus, this is the opportune time to review recent research progress on the development of 2D MOFs as electrodes in supercapacitors. This review covers synthetic design strategies, electrochemical performances, and working mechanisms. We will divide these 2D MOFs into two types on the basis of their conductive aspects: 2D conductive MOFs and 2D layered MOFs (including pillar-layered MOFs and 2D nanosheets). The challenges and perspectives of 2D MOFs are also provided.

An expeditious one pot green synthesis of novel bioactive 1, 4-dihydropyridine derivatives at ambient temperature and molecular modelling

In the presented synthetic work, a series of novel substituted 1, 4-Dihydropyridine derivatives (DHPs) have been prepared by the reaction of substituted aromatic aldehydes, ethyl acetoacetate, and ammonium acetate in the presence of a heterogeneous catalyst silica sulfuric acid at ambient temperature via expeditious, mild, inexpensive and one pot Hantszch multicomponent synthetic methodology. Various benefits of this approach are simple work-up; short reaction times at ambient reaction temperature, excellent yields, green solvent system, no by-products and purification of products without chromatographic separation. The catalyst was easily recovered by simple filtration and reused up to five times without washing with any solvent and without major loss in its activity. All the synthesized compounds were characterized by IR, 1H NMR, 13C NMR and LC-Mass spectroscopic techniques. Molecular modelling of the synthesized novel compounds with respect to Lipinski rule of five, drug likeness, toxicity profiles, drug score and other physico-chemical properties are described and compared with market available generic drugs. Theoretical screenings data suggested that the reported compounds possessed a broad range of lipophilic character, no toxicity risks and similar bioactivity scores as relative with standard drugs used for comparison.

Physico-chemical factors conditioning the electronic conduction of conductive polymers

The driving idea and the main objective of this synthetic work is the study of physicochemical factors such as the dielectric constant of the solvent, the polarizability of the chains and the Gap energy of the conductive polymers, these characteristics condition their properties. electrical and electrochemical. We focused our study on polyaniline, two synthetic methods are presented: chemical polymerization and electropolymerization with emphasis on the theoretical aspects of the phenomena involved as well as on the electrochemical methods used such as cyclic voltammetry. We have therefore developed with maximum clarity the links existing between the physico-chemical properties of polyaniline and its electrical conductivity.

Stereoselective total synthesis of (±)-vindeburnol and (±)-16-epi-vindeburnol.

A concise stereoselective total synthesis of (±)-vindeburnol and its epimer (±)-16-epi-vindeburnol is presented. This synthetic work features the utilization of Baeyer-Villiger oxidation to install different types of lactone substrate, and a sequence of aminolysis, aldimine condensation and acyl-Pictet-Spengler to deliver the crucial trans-fused indoloquinolizidine scaffold with high-level diastereocontrol.

Coevolutionary Dynamics of Organic-Inorganic Interactions, Hydrocarbon Generation, and Shale Gas Reservoir Preservation: A Case Study from the Upper Ordovician Wufeng and Lower Silurian Longmaxi Formations, Fuling Shale Gas Field, Eastern Sichuan Basin

Shale gas deposits are self-sourced, self-accumulating, and self-preserving in the Upper Ordovician Wufeng Formation and Lower Silurian Longmaxi Formation of the Fuling Shale Gas Field in the eastern Sichuan Basin. They were both seemingly mixed by secondary oil cracking and kerogen cracking gases during the high maturation window. The reservoir space primarily consists of mineral pores and organic matter (OM) pores, and the shale gas was mainly trapped by a high-pressure system. In this study, the Fuling O3w-S1l Shale Gas Field in the eastern Sichuan Basin was used as a case study to discuss the coevolutionary process and organic-inorganic interactions of hydrocarbon generation, accumulation, and preservation. The results indicate that the processes and mechanisms of organic-inorganic interactions and coevolution of hydrocarbon generation and reservoir preservation are quite different among the shale graptolite zones (GZ) with respect to hydrocarbon generation, types and characteristics of shale gas reservoirs, seal characteristics, and their spatiotemporal relations. In the WF2-LM4 GZ, the favorable OM, biogenic authigenic quartz and organic-inorganic interactions are highly coupled, leading to the high level of coevolution demonstrated within the field, as well as to the favorable conditions for shale gas accumulation. Conversely, the overlying LM5-LM8 GZ seemingly exhibits early densification and late charge and has a reverse mode of reservoir development (i.e., low degree of coevolution). These two coevolutionary processes were conducive to the development of a high degree of spatiotemporal matching between the reservoir (i.e., WF2-LM4 GZ) and the seal (i.e., LM5-LM8 GZ). This is due to underlying differences in their coevolutionary histories. The synthetic work presented here on the coevolutionary processes and mechanisms of formation for organic-inorganic interactions and hydrocarbon generation and reservoir preservation reveals insights into the driving mechanisms of shale gas enrichment, providing a basis for effectively predicting favorable enrichment intervals for shale gas worldwide.

PAVEL FLORENSKY’S CONCEPT OF THE ICON

This article is an analysis of the concept of the icon as seen by Pavel Florensky, a priest, philosopher of religion, and theologian. He expressed his views on the art of icon painting in the articles The Church Ritual as a Synthesis of the Arts, Devotional Icons of St. Sergius of Radonezh, and Reverse Perspective, as well as his work Iconostasis. Florensky’s theory is of great interest for art history, contributing to it not only by highly evaluating Russian icons of the 14th and 15th centuries but also by offering a new approach to realism in art. Yet as his concept is complex, it is also controversial. Viewing the icon as a work of art and following Plato’s philosophy, Florensky believes the objective reality of the Realm of Ideas to be the basis of artistic creativity in general and icon painting in particular. According to him, the creation of art is not an artist’s subjective search for the ways of self-expression but the result of the soul’s ascent to the truth, the world of prototypes. The icon reflects divine reality and is thus realistic in nature. Highly evaluating the icon painting in the 14–15 century Russia, he believes Andrei Rublev’s Holy Trinity to be an art masterpiece. However, developing his concept, Florensky discards the term “image”: for him, the icon is merely a symbol pointing to the prototype. The artistic image is born in the artist’s soul and exists independently from the icon, and can then be born in the soul of the beholder, who is guided to the prototype by the symbol. This is how the icon, as a result of artistic creation, is reproduced in the person viewing it. Florensky underlines the importance of aesthetics in assessing an icon, for a work’s artistic perfection is inseparable from its ability to testify to the prototype, and beauty is measured with the truthfulness of this testimony. Yet by acknowledging the fact that all icons created according to the canon are of the same value, he renounces the artistic criterion and makes the masterpieces of icon painting equal to many other artworks of average quality. For Florensky, the icon is an integral part of a synthetic work of art – the church ritual – and its existence as an art phenomenon is dependent on certain conditions: if these are not met, it “dies” as art.

Renieramycin-type alkaloids from marine-derived organisms: Synthetic chemistry, biological activity and structural modification.

Marine natural products are known for their diverse chemical structures and extensive bioactivities. Renieramycins, the member of tetrahydroisoquinoline family of marine natural products, arouse interests because of their strong antitumor activities and similar structures to the first marine antitumor agent ecteinascidin-743, approved by the European Union. According to the literatures, researches on the pharmacological activities of renieramycins mainly focus on their antitumor activities. In addition, by structural modification, derivatives of renieramycins show stronger antiproliferative activity and less accidental necrosis activity on cells. Nevertheless, the difficulties in extraction and separation hinder their further development. Hence, the synthetic chemistry work of renieramycins plays a key role in their further development. In this review, currently reported researches on the synthetic chemistry, pharmacological activities and structural modification of renieramycins are summarized, which will benefit future drug development and innovation.

Potency of natural and synthetic composites for ballistic resistance: A review

Mechanical characteristics of the laminated composite crafted from fabric type reinforcement perhaps inspired via the weaving method and reinforcement agent's usage due to each layer's constructional parameter. As a result, research on the arrangement configuration between bio composite and synthetic fibre for the material shape was proposed to enhance the composite structure's biodiversity and physical characteristics. Substitute for natural fibre in synthetic fibre composite works has shown the excessive capacity to be explored scientifically. The evaluation focused on the concept and essential of bio composite and the synthetic composite fabric positioned over the years from the previous studies of the preliminary researches. The sorts and features of matrix and fibre filler reinforcement materials in composites were also discussed. This assessment's main findings indicated that the composite centre relied on the weave styles and inter-ply and interplay lamination roles. Therefore, the state-of-the-art intraply for synthetic fibre and bio composite fibre in a composite shape was anticipated performing higher in mechanical energy, particularly within the application of ballistic resistance, besides decreased dependency on artificial fibre. It would ultimately suggest the excellent weave sample designs in the proper combination shape of natural and synthetic fibres embedded with polymers. The statistical results were compared with the experimental parameters available inside the literature review. The review explains approximately the studies and evolution within the enhancement of characteristic fibres reinforced polymer composites in ballistic resistance use. This paper goes over the body armour's profitable and present advancement materials, structure and development procedures, and related works on upgrading ballistic energy captivation and upgrading the mechanical tenacity for high impact resistance applications.

Synthesis, biological evaluation, and NMR studies of 3-fluorinated derivatives of 3′,4′,5′-trihydroxyflavone and 3′,4′,5′-trimethoxyflavone

Flavones are valuable scaffolds in medicinal chemistry, especially as they display activity as antioxidants and neuroprotective agents. The need to incorporate a fluorine atom on flavones has driven much of the recent synthetic work in this area. We now report a route for the production of 3-fluorinated derivatives of 3′,4',5'-trihydroxyflavone and 3′,4′,5′-trimethoxyflavone. Biological evaluation of these agents, along with their non-fluorinated counterparts, demonstrate that antioxidant activity may be enhanced whereas neuroprotective activity is conserved. Also, the 3-fluoro-3′,4',5'-trihydroxyflavone can act as an NMR probe to detect structural changes during its action as a radical scavenger.