Nagnnath D. Kokare

Water mediated efficient one-pot synthesis of bis-(4-hydroxycoumarin)methanes

Abstract Manganous chloride (MnCl2·4H2O) has been used as an efficient catalyst for an improved and rapid one-pot synthesis of bis-(4-hydroxycoumarin)methanes in excellent yields using water as a reaction medium. This aqueous mediated reaction of various aromatic and heteroaromatic aldehydes with 4-hydroxycoumarin using catalytic amounts of manganous chloride avoids the use of expensive, corrosive reagents, toxic solvents, and provides operational simplicity.

Design, Synthesis and Utilization of 1- Substituted Sulphonyloxy-2-Phenyl Benzimidazole as a Novel Peptide Coupling Reagents

Highly efficient coupling reagents, N-methanesulphonyloxy-2-phenyl benzimidazole and N - p-toluenesulphonyloxy-2-phenyl benzimidazole were designed, synthesized and successfully applied in peptide coupling reactions. Their efficiency was evaluated by synthesizing a number of structurally different amides and peptides as well. The distereomeric purity was examined by HPLC. Also the optical rotations of all the synthesized peptides were measured and found to be quite matching with corresponding values in literature. After completion of reaction, the N-hydroxy 2-phenyl benzimidazole which was the starting material for the synthesis of reagents could be easily isolated during the work up by acid base treatment and could be re-used without significant loss in reactivity. Also the intermediate in the reaction sequence was isolated and characterized by mass and (1)H NMR which could help to comment about the probable mechanism.

Efficient synthesis of β-acetamido ketones using BF3/Et2O: a fertile approach toward avoiding usage of acetyl chloride

Abstract A simple and efficient one pot synthesis of β-acetamido ketones from reaction of aldehydes, enolizable ketones, alkyl/aryl nitriles, and BF3/Et2O catalyst under microwave irradiations is described. This method allows synthesis of β-acetamido ketones without using corrosive and hazardous acetyl chloride. It is applicable for diversified aldehydes and active methylene ketones supported by synthesizing varieties of β-acetamido ketones. As per literature, majority of synthetic methods of β-acetamido ketones are restricted to use of acetonitrile lonely, as a nitrile component. This method is found to be equally effective for range of nitriles, also. Key features of reported method are simple reaction protocol, better yields, shorter reaction time, and nonhazardous reaction conditions which support the “Green Chemistry approach.”