Current Organic Chemistry - Volume 23, Issue 12, 2019

The polymeric graphitic carbon nitride (g-C3N4) has been one of the interesting earth abundant elements. Though g-C3N4 finds application as a photocatalyst, its photocatalytic behaviour is limited because of low efficiency, mainly due to rapid charge recombination. To overcome this problem, several strategies have been developed including doping of metal/non-metal in the cavity of g-C3N4. Moreover, the CoFe2O4 NPs have been used in many organic transformations because of its high surface area and easy separation due to its magnetic nature. This review describes the role of cobalt ferrite as magnetic nanoparticles and metal-doped carbon nitride as efficient heterogeneous catalysts for new carbon-carbon and carbon-hetero atom bond formation followed by heterocyclization. Reactions which involved new catalysts for selective activation of readily available substrates has been reported herein. Since nanoparticles enhance the reactivity of catalyst due to higher catalytic area, they have been employed in various reactions such as addition reaction, C-H activation reaction, coupling reaction, cyclo-addition reaction, multi-component reaction, ring-opening reaction, oxidation reaction and reduction reactions etc. The driving force for choosing this topic is based-on huge number of good publications including different types of spinels/metal doped-/graphitic carbon nitride reported in the literature and due to interest of synthetic community in recent years. This review certainly will represent the present status in organic transformation and for exploring further their catalytic efficiency to new organic transformations involving C-H activation reaction through coupling, cyclo-addition, multi-component, ring-opening, oxidation and reduction reactions.

Zanthoxylum, commonly known as Timoor, has been used in different traditional systems of medicine and also for several other applications such as chemopreventive agents, tooth care, as spices, condiments, etc. Due to the pungent taste of fruits, seeds, leaves, bark, and therapeutic remedies, especially in Indian system of medicine, Eastern Asian countries and in Central America, it is being substituted for pepper. The collection of Zanthoxylum armatum DC; Syn. Z. alatum Roxb and its several species used for food, medicine and barter has been a part of the culture of many communities in different countries. The fruits and seeds of timoor are well known in ayurvedic medicine and used for different diseases. The bark of the plant has also been reported for hepatoprotective activity. Several natural compounds have been isolated and identified in several classes, from different plant parts and species. The Zanthoxylum compounds and extracts of the plant parts have been reported for several types of biological activities. This review aims to examine the detailed aspects of phytochemical compounds and pharmacological activities covering maximum species of this genus. In view of the available pharmacological data and traditional use in Indian system of medicine and in other countries also, Z. armatum and other species certainly deserve more investigations. However, clinical evidence and rigorous investigations for quality control are required before any recommendation for Zanthoxylum based products.

The P-heterocyclic field forms a special part of organophosphorus chemistry, and is a special discipline within heterocyclic chemistry. The relevant results accumulated in the group of the author of this minireview in last 5 years are summarized. After surveying the conformational situation of cyclic phosphinates, their Microwave (MW)-assisted direct esterification and the T3P®-promoted esterification are discussed. The next chapters describe newer results regarding the interpretation and modelling of the rate enhancing effect of MWs, and on an important, but somewhat neglected field, the hydrolysis of phosphinates. New results on the ring enlargement of 5-membered unsaturated P-heterocycles to 6-ring species, as well as on the synthesis of 7-phosphanorbornene derivatives, and their refunctionalization are also included. Novel findings on the preparation of cyclic amides and imides are also explored. Last but not least, the user-friendly deoxygenations of cyclic phosphine oxides elaborated by us are shown. The reader will be able to discover green chemical considerations and accomplishments throughout the series of organophosphorus transformations reviewed.

This study reports the cross-metathesis of bicyclic β-pinene, acyclic cis-3- methylpent-2-ene terpenes and the natural rubber with functionalized olefins, a route for the functionalization of the carbon-carbon double bond of natural products to obtain aliphatic unsaturated esters. The production of unsaturated esters from β-pinene and cis-3- methylpent-2-ene via cross-metathesis reaction with dimethyl maleate and diethyl maleate in the presence of the ruthenium-alkylidene [Ru(Cl)2(=CHPh)(1,3-bis(2,4,6- trimethylphenyl)-2-imidazolidinylidene)(PCy3)] (I), [Ru(Cl)2(=CH(o-isopropoxyphenylmethylene))( 1,3-bis(2,4,6-trimethylphenyl) -2-imidazolidinylidene)] (II) and rutheniumvinylidene [RuCl2(=C=CH(p-C6H4CF3))(PCy3)2] (III) was carried out. Results showed that the reaction of β-pinene with diethyl maleate using II catalyst produced unsaturated esters with 43 % selectivity. I and III catalysts showed low activity toward the cross-metathesis of β-pinene and dimethyl maleate. A survey about the cross-metathesis of acyclic cis-3-methylpent-2-ene with diethyl maleate by II catalyst was also studied. The formation of ethyl but-2-enoate and ethyl-3-methylpent-2-enoate products was highly selective by 63 %. The unsaturated esters formation from the cross-metathesis degradation of natural rubber (99.9 % cis-polyisoprene) with dimethyl maleate and diethyl maleate using I-III catalysts was accomplished as well. I and II catalysts showed high activity in the degradation of natural rubber with diethyl maleate to produce the low molecular weight of oligomers unsaturated ester products (Mn = 1 x 103 g mol-1) with isoprene units of m = 10 – 27 and yields ranging from 68 to 94 %.

The emerging antifungal resistance represents a major challenge for the treatment of severe fungal infections, highlighting the need to develop novel and efficient antifungal compounds. This study aimed to synthesize new title compounds and screen them for their antifungal activity in order to generate highly accurate structure - activity relationships of 2-((4-chlorophenoxy)methyl)-N-(arylcarbamothioyl)benzamides and their de novo derivatives and to unveil some of their mechanisms of action by flow cytometry and fluorescence microscopy. The presence of functional groups was confirmed for nine new 2-((4- chlorophenoxy) methyl)-N-(arylcarbamothioyl)benzamides, using experimental and in silico methods. The antifungal activity was assessed against a broad spectrum of 26 yeast and filamentous fungal strains, using qualitative and quantitative assays. The results showed that Candida kefyr has been the most susceptible to all tested compounds, while 1b and 1f induced a strong inhibitory effect on the filamentous fungi Alternaria rubi, Aspergillus ochraceus and A. niger strains growth. The derivative 1c in subinhibitory concentrations alsoincreased the susceptibility of Candida albicans clinical strains to azoles. Predicted drug likeness and pharmacokinetics profiles of most active compounds were compared with the standard antifungal ketoconazole. Furthermore, the potentially more potent 1c and 1f derivatives were designed and studied regarding the chemical structure-biological activity relationship and pharmacokinetics profiles versus ketoconazole. The study confirms that the new benzamide derivatives exhibited an improved pharmacokinetics profile and a good antifungal activity, acting at least by increasing membrane permeability of fungal cells. Our results are recommending them as promising candidates for the development of novel therapeutic alternatives.