Substrate Directed Regioselective Monobromination of Aralkyl Ketones Using N-Bromosuccinimide Catalysed by Active Aluminium Oxide: α -Bromination versus Ring Bromination.

Bromination of aralkyl ketones using N-bromosuccinimide in presence of active Al2O3 provided either α -monobrominated products in methanol at reflux or mononuclear brominated products in acetonitrile at reflux temperature with excellent isolated yields depending on the nature of substrate employed. The α -bromination was an exclusive process when aralkyl ketones containing moderate activating/deactivating groups were subjected to bromination under acidic Al2O3 conditions in methanol at reflux while nuclear functionalization was predominant when aralkyl ketones containing high activating groups were utilized for bromination in presence of neutral Al2O3 conditions in acetonitrile at reflux temperature. In addition, easy isolation of products, use of inexpensive catalyst, short reaction time (10-20 min), and safe operational practice are the major benefits in the present protocol.

An efficient green multi-component reaction strategy for the synthesis of highly functionalised pyridines and evaluation of their antibacterial activities.

An efficient green multi-component reaction (MCR) method has been developed for the synthesis of 2-amino-4-aryl/heteroaryl-6-(pyridin-2-ylthio)pyridine-3,5-dicarbonitrile(s) via a 3-component reaction of aryl aldehyde(s), malononitrile and 2-mercaptopyridine in the presence of K2CO3 under solvent free reaction conditions (SFRC) using grinding technique at room temperature in a single step. The advantages of the present protocol is operationally simple, environmentally benign, solvent-free reaction conditions (SFRC), simple work up, excellent isolated yields of desired products and viable method for large scale applications in pharmaceutical industry. Interestingly, the synthesized compounds showed moderate to excellent antibacterial activities against Gram-positive and Gram-negative bacterial strains.