Browsing by Author "Parvin, Tasneem"

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    Development of new Synthetic Methodologies Leading to B-Amino Carbonyl Compounds:Some Aspects of Multicomponent Reactions
    (2009) Parvin, Tasneem
    This dissertation describes the successful efforts on the development of some new methodologies by multicomponent reactions for the synthesis of various b-amino carbonyl compounds using Lewis acid and bromodimethylsulfonium bromide as catalyst. The thesis contains mainly four chapters namely Chapter I, II, III and IV. Among them, the Chapter II and III are divided into two parts namely Section A and Section B. Chapter I describes the general introduction on multicomponent reaction and b-amino carbonyls. A brief literature survey on the recent advances in multicomponent reactions and importance of b-amino carbonyl compounds are highlighted in this chapter precisely. In Chapter II, we have described two new methodologies using very cheap and readily available Lewis acid catalysts for the four component one-pot synthesis of b-acetamido carbonyl compounds. Section A demonstrates a simple, efficient and greener protocol for the preparation of -acetamido carbonyl compounds using CeCl3 7H2O as a catalyst. The salient features of this protocol include operational simplicity, high yields of the products, avoidance of column chromatography, ready availability, low toxicity, moisture compatibility and reusability of the catalyst. Section B describes another new synthetic methodology using FeCl3 6H2O, a cheap, readily available, and efficient catalyst for the one-pot synthesis of -acetamido carbonyl compounds. The simplicity of the present protocol, high yields, and efficiency of the catalyst are the key features of this methodology. Due to the low cost and ready availability of the reagent FeCl3 6H2O, we prefer this protocol than our earlier reported method. Mechanistic investigations as well as variability of all the components in this transformation are addressed in this section. Both enolizable ketones and -keto esters are suitable for the preparation of corresponding b-acetamido carbonyl compounds under mild reaction conditions by these developed methods. Chapter III contains two new methodologies namely Aza-Michael and Mannich-type reaction using a versatile reagent bromodimethylsulfonium bromide as catalyst. A wide range of b-amino carbonyl compounds were synthesized by our developed methods..