Total Synthesis of Some Natural Unnatural Lignans Exploration of a Late Stage CSp3H Functionalization Logic

Abstract

The present thesis entitled Total synthesis of some natural/unnatural lignans: newlineExploration of a late-stage C(sp3)-H functionalization logic describes the development newlineof synthetic methodology to access dihydronaphthalenes and dihydronaphthoquinones newlinepresent in the cyclolignan class of natural products. Then, the application of the newlinemethodology for the total synthesis of pachypostaudin B has been demonstrated. In newlineaddition, the total synthesis of magnoshinin and merrilliaquinone has been accomplished newlinethrough the application of the methodology. Further, a [4+2] cycloaddition-based unified newlinestrategy has been successfully demonstrated for the syntheses of some natural and newlineunnatural cyclolignans such as gramineusquinone B, isomerrilliaquinone, isomagnoshinin, newlineand 2-epi-3,4-dihydromagnoshinin. Also, a silica-gel accelerated biomimetic Diels-Alder newlineapproach has been demonstrated for the total synthesis of magterpenoid C. Accordingly, newlinethe thesis has been divided into five chapters, and the chapter-wise details of the content are as follows.In chapter 1, ( Introduction, ) an overview and the background of lignans is newlinepresented. The significance of lignans synthesis is highlighted besides discussing the diverse class of lignans. Then, the biogenesis and bioactivity of cyclolignans is presented. newlineIn the second half of the chapter, in the context of the present thesis a review of some total newlinesynthesis efforts towards arylnaphthalene and aryl dihydronaphthalene type cyclolignans newlineare presented. Toward the end of chapter 1, the motivational factors and objectives set for newlinethe present thesis are delineated.Chapter 2: ( Organocatalyzed Late-Stage C(sp3)-H Functionalization and Chemoselective newlineOxidative Demethylation: Synthesis of Dihydronaphthalenes (DHNPs) and newlineDihydronaphthoquinones (DHNQs) ) deals with the synthesis of DHNP carboxaldehdyes newlineand DHNQ carboxaldehydes. The chapter commences highlighting the significance of newlinedeveloping methodology for DHNPs and DHNQs in context of cyclolignans.