K. P. Rakesh

An unexpected reaction to methodology: an unprecedented approach to transamidation

This report describes an unprecedented protocol for the synthesis of N,N′-substituted ureas using a cross-coupling method. Mono substituted ureas were modified by an economically viable and simple method using commercially available isocyanates and sodium hydride as the reagents. In addition, the method involves no expensive metal complexes or catalysts and all reactions are carried out at room temperature. Furthermore, both symmetrical and asymmetrical ureas were successfully obtained in single step reactions with reasonable yields.

Synthesis, SAR and molecular docking studies of benzo[d]thiazole-hydrazones as potential antibacterial and antifungal agents

A series of new benzo[d]thiazole-hydrazones analogues were synthesized and screened for their in vitro antibacterial and antifungal activities. The results revealed that compounds 13, 14, 15, 19, 20, 28 and 30 exhibited superior antibacterial potency compared to the reference drug chloramphenicol and rifampicin. Compounds 5, 9, 10, 11, 12, 28 and 30 were found to be good antifungal activity compared to the standard drug ketoconazole. A preliminary study of the structure-activity relationship (SAR) revealed that the antimicrobial activity depended on the effect of different substituents on the phenyl ring. The electron donating (OH and OCH3) groups presented in the analogues, increase the antibacterial activity (except compound 12), interestingly, while the electron withdrawing (Cl, NO2, F and Br) groups increase the antifungal activity (except compound 19 and 20). In addition, analogues containing thiophene (28) and indole (30) showed good antimicrobial activities. Whereas, aliphatic analogues (24-26) shown no activities in both bacterial and fungal stains even in high concentrations (100µg/mL). Molecular docking studies were performed for all the synthesized compounds of which compounds 11, 19 and 20 showed the highest glide G-score.

Arylnaphthalene lactone analogues: synthesis and development as excellent biological candidates for future drug discovery

Arylnaphthalene lactones are natural products extracted from a wide range of different parts of plants. The progressing interest in the synthesis of these compounds is due to their significant biological activities, which have made them potential candidates in drug discovery and development. This review mainly covers recent developments in the synthesis and biological applications of arylnaphthalene lactone analogs.

Recent Development of Sulfonyl or Sulfonamide Hybrids as Potential Anticancer Agents: A Key Review

Cancer is the second leading cause of death worldwide. There is always a huge demand for novel anticancer drugs and diverse new natural or synthetic compounds are developed continuously by scientists. Presently, a large number of drugs in clinical practice have showed pervasive side effect and multidrug resistance. Sulfonyl or sulfonamide hybrids became one of the most attractive subjects due to their broad spectrum of pharmacological activities. Sulfonyl hybrids were broadly explored for their anticancer activities and it was found that they possess minimum side effect along with multi-drug resistance activity. This review describes the most recent applications of sulfonyl hybrid analogues in anticancer drug discovery and further discusses the mechanistic insights, structure-activity relationships and molecular docking studies for the potent derivatives.

Pd-Catalyzed one-pot dehydroxylative coupling of phenols with K4[Fe(CN)6] mediated by SO2F2: a practical method for the direct conversion of phenols to aryl nitriles

We have developed a Pd-catalyzed direct dehydroxylative cyanation of phenols by employing an inexpensive food additive, potassium ferrocyanide (K4[Fe(CN)6]), as the cyanating reagent instead of highly toxic cyanide salts. This protocol provides a strategically distinct approach for the preparation of aryl nitriles in a safe, mild, convenient and practical manner.

Carbonyl–olefin metathesis: a key review

In organic chemistry, olefin–olefin metathesis of two unsaturated substrates for the formation of a new carbon–carbon bond has been widely explored and applied. Exploration of the construction of a carbon–carbon bond through the carbonyl–olefin metathesis reaction remains limited but has recently attracted significant interest and attention. This review covers most of the strategies involving metal-mediated, metal-free intramolecular, photochemical, Lewis acid-mediated, and catalytic carbonyl–olefin metathesis (e.g., ring-closing metathesis, ring-opening metathesis, and cross-metathesis). The necessity of stoichiometric amounts of transition metals with the synchronized formation of kinetically inert metal oxo species, which prevented the regeneration of the active metal catalyst, has most likely been the main reasons for the insignificance of the carbonyl–olefin metathesis reaction. Developing catalytic carbonyl–olefin metathesis is still a current challenge in organic synthesis.

Vision for medicine: Staphylococcus aureus biofilm war and unlocking key's for anti-biofilm drug development

The Staphylococcus aureus biofilm-associated burden is challenging to the field of medicine to eradicate or avoid it. Even though a number of S. aureus biofilm mechanisms understood and established the possible ways of biofilm formation but, still need to know more and require a development of new therapeutic strategies. In this viewpoint, we discuss the underlining biofilm mechanism, its existing systems as active therapeutic agents and as vehicles to transport drugs to the site of infection. The step-back in drug development is due to the emergence of antibiotic-resistant S. aureus. The understanding of bacteria/biofilms is an aspect that we likewise summarize for possible drug development for future as medicine against resistant S. aureus was viewed.

Master mechanisms of Staphylococcus aureus: consider its excellent protective mechanisms hindering vaccine development!

Lack of known mechanisms of protection against Staphylococcus aureus in humans represents an important risk factor for skin infections and bacteremia in patients, intern hindering the development of efficacious vaccines. However, development of effective humoral response may be dampened by converging immune-evasion mechanisms of S. aureus. To develop a promising vaccine against S. aureus, it is pre-requisite to clear understanding of cutaneous, innate and adaptive immune response. The S. aureus dampening the humoral response, T cell help, blocking complement factors, and killing immune players by its toxins are the important factors need to understand clearly. We hypothesized that the master mechanism of S. aureus counteracts may hindering the immune action which may result in failure of target-oriented vaccine development. Developing immunological interventions that can effectively block the S. aureus counteracting mechanisms are the key success for a developing vaccine for the future was warranted.

Role of BP*C@AgNPs in Bap-dependent multicellular behavior of clinically important methicillin-resistant Staphylococcus aureus (MRSA) biofilm adherence: A key virulence study.

Bacterial adhesion is a threshold event in the formation of biofilms which leads to serious bacterial diseases. This shows that the underlining the problem is interesting and need to solve the problem of biofilm-related complications. To support this, in the present study, we first time initiated to understand the role of methicillin-resistant Staphylococcus aureus (MRSA) biofilm using previously developed benzodioxane midst piperazine decorated chitosan silver nanoparticles (BP*C@AgNPs). The BP*C@AgNPs studied for antimicrobial, anti-biofilm, biofilm adherence inhibition, the role of ions in biofilm, and an antibiotic cocktail in the treatment of biofilm was assessed. The results showed that, the significant biocidal role of BP*C@AgNPs in controlling the MRSA biofilm and interaction of biofilm protein to calcium ions were significantly decreased. This confirms that calcium ion involved in the biofilm formation and for the treatment of BP*C@AgNPs, cocktail of enzyme and antibiotic have the promising therapeutic value was observed. In future the locking of biofilm protein and its expression in presence of calcium ion was interesting, and greater application related to biofilm infection was warrantable.

Visible-light initiated aerobic oxidations: a critical review

The development of new and highly efficient strategies for the rapid construction of complicated molecular structures has huge implications and remains a preeminent goal in present day synthetic chemistry. In the past ten years, visible light promoted aerobic oxidations have been emerging as one of the fastest growing fields in organic chemistry because of their low cost, easy availability and environmental friendliness. This review describes and highlights the scope and limitations, recent research progress in novel methodology development, and applications in organic synthesis, as well as the mechanisms of these visible light promoted aerobic oxidation reactions. The discussion contains several sections based on the following reaction types: (1) alcohols to aldehydes; (2) amines to nitriles; (3) methylarenes to aldehydes; (4) boronic acids to phenols; (5) formation of carbonyl compounds or ketones; (6) β-keto sulfones; (7) sulfoxides; (8) amine to amide; and (9) some other reactions.