Design, synthesis and spectral studies of novel heterocyclic compounds

Abstract

The pyrazolines are the five membered heterocyclic compounds which have attracted the attentions of organic chemists in the past decades due to their immense biological applications. These compounds are generally prepared from the reactions of chalcones with hydrazine derivatives under the ordinary conditions. So, this thesis has been devoted upon the synthesis and antibacterial examinations of variously substituted pyrazolines and bispyrazolines. In the chapter-I of the thesis are described the examples of various heterocyclic compounds from the literature and it was found that five membered heterocyclics containing two and three hetero atoms are associated to the useful pharmacological properties. The chapter-IIa describes results of investigations relating to the cyclocondensation reactions of the thienyl/furyl-alkoxychalcones with phenyl hydrazine under the acidic alcoholic medium. These reactions could lead to the formation of two series of thienyl/furyl substituted alkoxy-N-phenyl pyrazolines. The chapter IIb provides the easy synthesis of alkoxy-N-thiocarbamoyl-pyrazolines which are obtained from the cyclization reactions of alkoxy-chalcones with thiosemicarbazide under the alcoholic alkaline conditions. In the chapter-III synthesis of new alkoxy substituted 1,3,4 thiadiazolines have been described and these products are obtained from the cyclization reactions of alkoxythiosemicarbazones with acetic anhydride. The reactions of intermediate thiosemicarbazones with 2,3-dichloroquinoxaline also resulted in the formation of new thiazoles. The required thiosemicarbazones were obtained from the reactions of alkoxy-benzaldehydes with thiosemicarbazide. The Chapter-IVa contains the cyclocondensation reactions of furyl/thienylbischalcones with phenyl hydrazine and these reactions could furnish N-phenyl-bispyrazolines as the end products. The chapter IVb describes the synthesis of new N-thiocarbamoyl-pyrazolines which are easily prepared from the cyclization reactions of alkyl chain linked bischalcones