N. C. Gangi Reddy

Synthesis of alkynyl/alkenyl-substituted pyridine derivatives via heterocyclization and Pd-mediated Sonogashira/Heck coupling process in one-pot: a new MCR strategy

A new class of 2-amino-4-(3/2-(alkynyl)/3-(alkenyl)phenyl)-6-phenylnicotinonitriles (6, 7 & 9) has been synthesized with good to excellent isolated yields by the multi-component reaction (MCR) of bromobenzaldehyde (1), malononitrile (2), acetophenone (3), NH4OAc (4) and a series of terminal alkynes (5)/alkenes (8) in the presence of pyrrolidine and Pd-catalyst in a mixture of H2O–DME (1 : 4 ratio) under reflux conditions in a single step. The Heck-type coupling with terminal olefins takes place stereoselectively with exclusive formation of E-isomers. This new MCR strategy opens new avenues in the development of (i) a diversity-oriented new cyanopyridine based compound library and (ii) new chemical entities other than the present reported molecules.

Lactic acid-mediated tandem one-pot synthesis of 2-aminothiazole derivatives: A rapid, scalable, and sustainable process

Abstract Environmentally benign and biodegradable lactic acid is identified as alternative solvent and catalyst for the tandem one-pot synthesis of Hantzsch 2-aminothiazole derivatives (4) from readily available aralkyl ketones (1) through in situ regioselective α-bromination using N-bromosuccinimide (2) followed by heterocyclization using thiourea (3) at 90–100°C. The major advantages of the present method include short reaction times (10–15 min), practical, simple to perform, easy work-up, good yield of products (up to 96%), productive for large-scale applications, free from apply of α-bromoketones (lachrymator) as substrates, avoids column purification. Hence, the present method meets with the concepts of both Wender’s “ideal synthesis” and sustainable chemical process.

Discovery of a new class of 16-membered (2Z,11Z)-3,11-di(aryl/naphthyl)-1,13-dioxa-5,9-dithia-2,12-diazacyclohexadeca-2,11-dienes as anti-tumor agents

A series of new 16-membered small macrocyclic compounds, (2Z,11Z)-3,11-di(aryl/naphthyl)-1,13-dioxa-5,9-dithia-2,12-diazacyclohexadeca-2,11-dienes (1a–k) were designed and developed by a simple and practical synthetic route from readily available substrates using simple organic transformations. Evaluation of in vitro anti-tumor activities on human triple negative breast cancer cells MDAMB-231 cell lines reveal that the macrocycles, 1a, 1f, 1g, 1i and 1k are promising anti-tumor compounds as evidenced from inhibition of cell migration and proliferation, upregulation of anti-tumor genes p53, MDA7 and TRAIL. The anti-proliferative effect of macrocycles is specific to cancer cells but no cytotoxic effect on normal breast epithelial cells has been observed (MCF10A). The developed synthetic route is free from metals, protecting groups and air-free techniques. The structure of macrocycle (1e) is confirmed by single crystal XRD studies.

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.