title: Facile diversity-oriented synthesis and antitubercular evaluation of novel aryl and heteroaryl tethered pyridines and dihydro-6H-quinolin-5-ones derived via variants of the Bohlmann-Rahtz Reaction.
abstract: The diversity oriented synthesis of substituted pyridines and dihydro-6H-quinolin-5-ones tethered with aryls and heteroaryls was achieved in very good yields through CeCl(3)·7H(2)O-NaI catalyst via variants of the Bohlmann-Rahtz reaction. β-Enaminones derived from various aryl and heteroaryl methyl ketones were regioselectively reacted with ethyl acetoacetate or 5,5-dimethylcyclohexane-1,3-dione or 4,4-dimethylcyclohexane-1,3-dione and ammonium acetate refluxing in 2-propanol. Applicability of nontoxic cerium catalyst, high reactivity with wide range of aryl and heteroaryl β-enaminones leading to diverse analogues, operational simplicity, and shorter reaction time at comparatively low temperatures are prominent features of the developed protocol. These synthesized substituted pyridines and dihydro-6H-quinolin-5-one analogues have been evaluated for their in vitro antimycobacterial activity against Mycobacterium tuberculosis H37Rv (MTB) by agar dilution method. Among the 48 compounds screened, six compounds 2-(5-chlorothiophen-2-yl)-7,7-dimethyl-7,8-dihydro-6H-quinolin-5-one 4{13,2}, 2-(5-bromothiophen-2-yl)-7,7-dimethyl-7,8-dihydro-6H-quinolin-5-one 4{14,2}, 2-(5-chloro thiophen-2-yl)-6,6-dimethyl-7,8-dihydroquinolin-5(6H)-one 4{13,3}, and 2-(5-bromothiophen-2-yl)-6,6-dimethyl-7,8-dihydroquinolin-5(6H)-one 4{14,3}, 7,7-dimethyl-2-(naphthalen-2-yl)-7,8-dihydroquinoline-5(6H)-one 4{6,2}, 6,6-dimethyl-2-(naphthalen-2-yl)-7,8-di hydroquinolin-5(6H)-one 4{6,3} resulted as the most promising antitubercular agents.
authors.affiliation: Organic Chemistry Division-II, Indian Institute of Chemical Technology, Hyderabad, India. kantevari@yahoo.com
authors.forename: Srinivas
authors.initials: S
authors.lastname: Kantevari
authors.forename: Santhosh Reddy
authors.initials: SR
authors.lastname: Patpi
authors.forename: Dinesh
authors.initials: D
authors.lastname: Addla
authors.forename: Siddamal Reddy
authors.initials: SR
authors.lastname: Putapatri
authors.forename: Balasubramanian
authors.initials: B
authors.lastname: Sridhar
authors.forename: Perumal
authors.initials: P
authors.lastname: Yogeeswari
authors.forename: Dharmarajan
authors.initials: D
authors.lastname: Sriram
mesh_terms: D000995:Antitubercular Agents / Q000138:chemical synthesis / Q000494:pharmacology; D002384:Catalysis; D002563:Cerium / Q000737:chemistry; D020650:Combinatorial Chemistry Techniques / Q000379:methods; D015394:Molecular Structure; D009169:Mycobacterium tuberculosis / Q000187:drug effects; D011725:Pyridines / Q000138:chemical synthesis*; D015363:Quinolones / Q000138:chemical synthesis* / Q000494:pharmacology; D054852:Small Molecule Libraries / Q000138:chemical synthesis*; D013329:Structure-Activity Relationship
chemical_list: D000995:Antitubercular Agents; D011725:Pyridines; D015363:Quinolones; D054852:Small Molecule Libraries; D002563:Cerium