RESULTS:

Background: Due to significant biological activity associated with N- O- and Sheterocycles a number of reports for their synthesis have appeared in recent decades. Traditional approaches require expensive or highly specialized equipment or would be of limited use to the synthetic organic chemist due to their highly inconvenient approaches. This review summarizes the applications of platinum metal with emphasis of their synthetic applications for heterocylces. In summary this review article describes the synthesis of different sized heterocyclic rings containing different heteroatoms. Objective: The key area of research these days is the development of rapid efficient and versatile tools for the construction of heterocycles and much prominence was gained by protocols that involved transition- metal catalysis. The traditional strategies that involved long reaction times harsh conditions and limited substrate scopes are overshadowed by these catalytic practices. Conclusion: The efficient and chemoselective synthesis of heterocycles by this technique has appeared as an important tool. This review shows a highly dynamic research field and the employment of platinum catalysts in organic synthesis. Several strategies have been pointed out in the past few years to meet more sustainable efficient and environmentally benign chemical products and procedures. The catalytic strategies have been the focus of intense research because they avoid the use of toxic reagents. Among these catalytic strategies highly rewarding and an important method in heterocycles synthesis is metal catalyzed synthesis.

This review article discusses about various aspects that make graphene and graphene nanosheets/binary transition metal oxide (GNS/BTMO) composites apt for their use as anode materials in lithium ion batteries (LIB). GNS/BTMO composites are categorized into three types based on the type of local contact between GNS and BTMO in the composites. These three types are zero-dimensional one-dimensional and two-dimensional contact composites which are elaborately explained in this article. Amongst the three type the two dimensional contact composites show superior electrochemical properties (suitable for consideration as anode materials in LIB) than the other two types of contact composites owing to the presence of highly conducting graphene and enhanced local interaction between GNS and BTMO which constrains the restacking of GNS and aggregation of BTMO.

Background: Nanotechnology has provided significant benefits to photodynamic therapy (PDT) which has revolutionized treatments of several diseases. The success of this versatile technique is governed by the sequential in situ generation of reactive oxygen species after a suitable photosensitizer has been irradiated by a defined wavelength of light. While PDT provides a minimally-invasive and convenient method for the treatment of several afflictions the efficiency of this therapeutic strategy still has potential for improvements. Several bodies of works within this realm have highlighted the use of inorganic compounds which is pivotal for the development of photosensitizers (PSs) nanoparticles (NPs) and irradiation sources. Methods: The past decade of online patented reports based on PDT were reviewed. Results: The patented reports analyzed showcased the integration of nanomaterials and inorganic compounds into PDT. The patents were grouped according to the following categories viz. “Nanoparticles in Photodynamic Therapy” “Photosensitizers Incorporating Various Metal Centers” and “Modifications to Light Delivery”. Conclusion: PDT is a suitable treatment option for several diseases however there are several challenges and limitations. The incorporation of NPs in the field of PDT is an extremely promising avenue which can be utilized to improve the execution of PDT. Furthermore the use of inorganic compounds was noted to be frequented in the development of PSs and NP conjugates. The patents presented addressed the associated problems with PDT but there still remains an opportunity for continued research efforts so that more clinical applications are possible.

Cholinesterase activity associated with neuritic plaques (NPs) and neurofibrillary tangles (NFTs) in Alzheimer's disease (AD) brains exhibit altered histochemical properties such as requiring lower pH (6.8) for optimal cholinesterase staining compared to the pH (8.0) for best visualization of cholinesterases in neurons. Furthermore visualization of NPs and NFTs can be prevented by agents like the peptidase inhibitor/metalloantibiotic bacitracin. The anomalous behavior of cholinesterases associated with pathological lesions needs to be elucidated because of the putative links between these enzymes and the disease process in AD. In this study cholinesterases were extracted from AD and normal brain tissue to determine whether the differences observed in histochemical analyses in the two sources were reflected in kinetic properties measured in solubilized enzymes. Isolated brain enzymes from both these sources exhibited comparable kinetic parameters with respect to pH dependence substrate affinity and inhibitor sensitivity and were not significantly affected by other agents that blocked cholinesterase histochemical visualization such as the structurally diverse metalchelating antibiotics bacitracin doxycycline minocycline and rifampicin. Although the cholinesterases from AD brain tissue examined here represented a total pool of these enzymes from AD brain rather than enzymes specifically from NPs and NFTs their kinetic behavior being comparable to cholinesterases isolated from normal brain tissues implies that these enzymes do not undergo disease-related modification in their primary structures. This suggests that the atypical histochemical behavior of cholinesterases in NPs and NFTs may result from interaction of cholinesterases with other molecules within these lesions mediated by transition metal ions known to be present in AD pathology lesions.

The cheaper and less-toxic metals of group 4 compared with common metals used in catalysis are increasingly applied in catalysis resulting in the development of many novel greener transformations. Zirconium is abundant non-toxic and exhibits a remarkably diversified chemical reactivity among these metals. Since the first asymmetric zirconium-catalyzed reaction disclosed by Nugent in 1992 a wide variety of chiral zirconium catalysts have been proven to be capable of promoting many types of highly enantioselective transformations spanning from standard reactions such as Friedel-Crafts reactions cycloadditions aldol reactions Mannich reactions epoxidations nucleophilic additions to carbonyl compounds and derivatives cyanations ring-opening reactions hydroxylations hydroformylations carboaluminations among others to more modern and complex domino and tandem processes. This review aims to collect the major progress achieved in the field of enantioselective transformations of all types promoted by chiral zirconium catalysts covering the literature since the beginning of 2003 and illustrating the power of these non-toxic catalysts to provide high enantioselectivity in almost all kinds of asymmetric organic reactions. It is divided into ten parts focussing consecutively on enantioselective Friedel-Crafts reactions cycloadditions aldol reactions Mannich reactions epoxidations additions of alkylzinc reagents to imines cyanations ring-opening reactions hydroxylations and domino/ tandem reactions. The diversity of these transformations well reflects that of the products synthesized. For example chiral indole and pyrrole derivatives were prepared from Friedel-Crafts reactions; pyranones pyridones and pyrazolidines from cycloadditions; β-hydroxy α-diazo carbonyl compounds β- hydroxy (thio)esters and β-hydroxy-α-amino acid derivatives from aldol reactions; β-amino (thio)esters from Mannich reactions; functionalized epoxides from epoxidations; amines from additions of alkylzinc reagents to imines; amino nitriles from cyanations; 12-diamines and β-vinyloxy alcohols from ring-opening processes; 2- hydroxy 1-indanones from hydroxylations; various amines 13-anti-diol monoesters β-amino esters αβ- dihydroxy acid derivatives α-amino ketones indoles cyclopentane and aryl α-aminophosphonates from domino/ tandem reactions. Furthermore the utility of these novel methodologies was demonstrated in the total synthesis of numerous essential bioactive products such as (+)-prelactone C (+)-9-deoxygoniopypyrone (+)- coniine vancomycin (+)-fusarisetin A mycolipenic acid onchidin indoxacarb tachykinin receptor antagonists cerebroprotecting agent MS-153 and L-erythro-sphingosine. The advances achieved in the last three decades demonstrate that the non-toxicity abundance and efficiency of zirconium make its application in catalysis suiting the growing demand for more environmentally benign processes offering the real opportunity to replace other toxic and expensive metals in the near future.

Reactive oxygen species (ROS) are continuously generated in living cells mainly as a consequence of aerobic metabolism. If ROS production exceeds the capacity of antioxidant systems oxidative stress may induce damage in all cellular macromolecules. Hypoxia derived from inappropriate and inadequate vasculature is a characteristic of rapidly proliferating tumors. A hypoxic environment promotes ROS production which further activates hypoxia-derived pathways e.g. those regulated by hypoxia inducible factor 1. Based on the increasing and significant amount of data available already hypoxia and oxidative stress are widely linked to many stages of carcinogenesis. On the other hand the effects of the major chemotherapeutics used in the treatment of gynecological cancers are based directly or indirectly on the excessive production of ROS and high antioxidant levels can increase resistance to these drugs. The measurement of tumor hypoxia oxidative stress markers and antioxidant levels may become potential predictive and prognostic biomarkers in the future as already is the case in some types of carcinomas. Either by down or upregulating ROS levels in tumor cells may provide novel pharmacological interventions in the treatment of these malignancies. There are currently several anticancer redox drugs in various phases of pre-clinical and clinical trials which will be discussed in this review.

Optically pure 11′-bi-2-naphthol (BINOL) and its derivatives are among the most widely used chiral ligands and auxiliaries for asymmetric synthesis. These molecules also occur as scaffolds for various biologically active compounds. Direct oxidative coupling of 2-naphthols in the presence of chiral catalysts provides a powerful strategy for the synthesis of optically pure 11′-bi-2-naphthols (BINOLS). In 1978 Wynberg with co-workers discovered that a copper salt with chiral auxiliary mediates the oxidative coupling of 2-naphthols which can be taken as the starting point for further progress in this area. Over the last decades a number of efficient and stereoselective catalyst systems have been developed. This mini-review surveys the aerobic asymmetric oxidative coupling of 2-naphthols catalyzed by transition metal complexes reported since 1995.

Mycobacterium tuberculosis (M. tuberculosis) an almost genetically monomorphic pathogen is a human parasite transmitted mostly by humans and causes tuberculosis (TB). TB is firmly associated to poverty although lack of proper nutrition and lowered immune status are contributing factors for disease development. TB remains second only to HIV/AIDS as the leading cause of mortality worldwide due to a single infectious agent and is responsible for nearly 1.5 million deaths annually. Some steps of the progress of our knowledge of M. tuberculosis physiology and its interactions with human beings are reviewed here. This progress has provided fertile ground for improving diagnosis and cure of TB infection. For TB diagnostics laboratories in high-burden countries primary isolation is the first step before performing drug susceptibility testing (DST) of M. tuberculosis. IGRA (interferon-γ release assay)-based tests for diagnosis of active TB are sufficiently fast specific and sensitive to allow to contain infection and distinguish among latent TB infection and BCG vaccination individuals from those who have clinically resolved M. tuberculosis infection after anti-TB treatment.

The aldol reaction of acetate and methyl ketone-based donors with aldehyde acceptors is reviewed. Emphasis is placed on major advances reported in the last 10-15 years. Several methods for inducing chirality at the newly formed stereogenic center are discussed including popular alternate methods for equivalent syntheses. Different methods for stereospecific synthesis are compared in terms of yield selectivity ease of synthesis and applicability to both small molecule and large macrolide production.

Over the last few decades transition metal-catalyzed direct C-H activation with the assistance of a coordinating directing group has emerged as an atom- and stepeconomical synthetic tools to transform C–H bonds into carbon-carbon or carbonheteroatom bonds. Although the strategies involving regioselective C–H cleavage assisted by various directing groups have been extensively reviewed in the literature we now attempt to give an overview of the recent advances on phosphorus-containing functional group assisted C-H activation reactions catalyzed by transition-metal catalysts including mechanistic study and synthetic applications. The discussion is directed towards C-H olefination C-H activation/cyclization C-H arylation C-H amination C-H hydroxylation and acetoxylation as well as miscellaneous C-H activation.