Abstract:The isocoumarins are naturally occurring lactones that constitute an important class of natural products exhibiting an array of biological activities. A wide variety of these lactones have been isolated from natural sources and, due to their remarkable bioactivities and structural diversity, great attention has been focused on their synthesis. This review article focuses on their structural diversity, biological applications, and commonly used synthetic modes.

Silver(I) complexes of 2-mercaptopyridine (Mpy), [Ag(Mpy)]NO3and [Ag(Mpy)2]NO3, and the first mixed-ligand complex having a thione and thiolate coordinated to Ag(I), [Mpy–Ag–Tm] (Tm═thiomalate) have been prepared and characterized by IR and NMR spectroscopy. The1H and13C NMR spectra show the presence of both ligands in the mixed-ligand complex, [Mpy–Ag–Tm]. An upfield shift is observed in the >C═S resonance of Mpy and C═O resonances of thiomalate in13C NMR, while the other resonances are shifted downfield. The complexes showed relatively high antibacterial activity (inhibition zone of 6–11 mm) against a gram +ve bacterium,Bacillus subtilis, as compared to that (inhibition zone of 4 mm) against a gram –ve bacterium,Escherichia coli.

Quinoline forms the key skeletal component of a number of important natural products and pharmacologicallyactive compounds. Despite a tremendous amount of research pertaining to the derivatization of quinoline, very few general synthetic routes are described in the literature starting from quinoline or tetrahydroquinoline. A simple and convenient method for the polyfunctionalization of quinolines via nitration of bromoquinolines has been developed. This method represents a new synthetic approach to convert brominated nitroquinoline derivatives into useful cyclic amines via nucleophilic-substitution (SNAr) reaction.

Heavy metals e.g., Hg, Cd, Cr, Pb, Zn, As and Ni etc are a major sources of pollutants which enter into the food chains and cause serious health impairments, carcinogenicity and mutagenesis. They have adverse effects on blood composition, lungs, energy level, kidneys, central nervous system, liver, and other vital organs of the body. Heavy metals can be successfully removed by easily available, eco-friendly and low-cost adsorbents which include the wastes/products of natural (chitin, silicate porous material, clay and zeolites, vermiculite, cyclodextrin, chitosan, starch and its derivatives, alginates, fly ash), agricultural (walnut shell, Turkish coffee, waste tea, black gram, neem bark, coconut shell, coconut husk, coal, oil palm shell, sugarcane bagasse, rice, wool, waste tea, peat moss, Turkish coffee, exhausted coffee, crop biomass, rice straw, rice hulls, rice husk, rice, soybean hull, papaya wood, peanut shell, peanut, citrus fruits, palm date pits, black gram, wool, cassava waste, carrot residues, banana and orange peels, sugar-beet pectin gels, black gram husk) and industrial (waste rubber tire, waste slurry, lignin, fly ash, red mud)) origin. The adsorption efficiency is affected by functional groups and particle/ pore size of the adsorbent, speed of agitation, biosorbent dose, initial concentration and molecular size of metal ions, temperature and pH.

A variety of chiral derivatives of benzo[d]naphtho[1,2-b]pyran-6-one were prepared in a single step by Et3 N-mediated condensation of homophthalic anhydride with different derivatives of (S)-amino acid chlorides at -5 °C by employing a chiral pool methodology.