Bhupender S. Chhikara

KF-Alumina Immobilized in Ionic Liquids: A Novel Heterogeneous Base for Heterocyclization of Alkylsulfanylphenylamines into 1,4-Benzothiazine

A rapid and convenient synthetic methodology for the cyclocondensative transformation of various alkylsulfanylphenylamines with bromoacetyl bromide by supporting on KF-alumina in ionic liquids [bmim][Br] and [bmim][BF 4 ] has been developed to obtain 3-oxo-1,4-benzothiazine in good yields. The product is easily obtained by extraction with ethyl acetate and concentrating under vacuum. Easy recovery of ionic liquid and use in consecutive reactions is also reported.

IMPACT OF MICROWAVE RADIATIONS ON MACROCYCLIZATION REACTIONS: SOLVENT FREE SYNTHESIS OF 1,4-BENZOTHIAZIN-3-ONE DERIVATIVES ON BASIC ALUMINA

A rapid transformation of alkyl and arylalkyl amino phenyl thioethers (2-alkylsulphanyl-phenylamine) into 7substituted 1,4-benzothiazines in presence of basic-alumina under solvent free conditions using microwave irradiation has been described. The specific microwave effects are due to increase in polarity during the course of reaction. Introduction Microwave assisted organic synthesis has attracted a substantial amount of attention in recent years. The practical advantages associated with microwave-assisted reaction are enhanced reaction rates, high yields, improved selectivity and environment-friendly reaction conditions (1). Several methods have been developed for performing reaction with microwave irradiation in solution and under solvent free conditions (2 ) . Applications of microwave irradiation in organic synthesis have seen considerable growth to improve the selectivity, rate enhancement and reduction of thermal degradative by-product. Furthermore, the combination of microwave and inexpensive mineral solid supports such as alumina, silica and clay allows the rapid and high yield of various organic molecules (3,4). The 3-0X0-3,4-dihydro-2H-l,4-benzothiazine 1 is an important intermediate for the synthesis of various biologically active compounds (5). 2-substituted and N-alkyl bridgehead cyclo-aza derivatives of 3-oxo3,4-dihydro-2H-l,4-benzothiazine are potential antimicrobial and antifungal agents (6). The 1,4-benzothiazine has also been reported to be central motif for various molecules which has found to posses potential Aldose Reductase inhibition (7), Ca antagonism (8) immunomodulating properties, antagonism of a-andrenoreceptor (9) and anti-inflammatory activity (10). Various methods have been reported for the synthesis of 1,4benzothiazines such as from 2-aminothiophenol (11), a-(o-Nitrophenylthio) acids (12), o-aminophenyl sulphide (13). In this paper synthesis of 1,4-benzothiazines from various 2-alkylsulphanylphenylamines (2a-n) under microwave radiations on basic alumina (Schemel) are repotred.

Multistage inhibitors of the malaria parasite: Emerging hope for chemoprotection and malaria eradication

Over time, several exciting advances have been made in the treatment and prevention of malaria; however, this devastating disease continues to be a major global health problem and affects millions of people every year. Notably, the paucity of new efficient drug molecules and the inevitable drug resistance of the malaria parasite, Plasmodium falciparum, against frontline therapeutics are the foremost struggles facing malaria eradication initiatives. According to the malaria eradication agenda, the discovery of new chemical entities that can destroy the parasite at the liver stage, the asexual blood stage, the gametocyte stage, and the insect ookinete stage of the parasite life cycle (i.e., compounds exhibiting multistage activity) are in high demand, preferably with novel and multiple modes of action. Phenotypic screening of chemical libraries against the malaria parasite is certainly a crucial step toward overcoming these crises. In the last few years, various research groups, including industrial research laboratories, have performed large‐scale phenotypic screenings that have identified a wealth of chemical entities active against multiple life stages of the malaria parasite. Vital scientific and technological developments have led to the discovery of multistage inhibitors of the malaria parasite; these compounds, considered highly valuable starting points for subsequent drug discovery and eradication of malaria, are reviewed.

WITHDRAWN: Evaluation of aromatic bifunctional chelating agents conjugated with Biotin for pretargeting of EAT tumor with avidin.

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