Chemical transformations of abundant natural products

Abstract

Tagitinin-E has been synthesized from tagitinin-C(3), thus leading to a revised structure for tagitinin-E(7). Ciliarin (19a) and orizabin (21a) have been synthesized from tagitinin-C(3) which delineates the question about the absolute stereochemistry of the ester side chain at C-8. Since calaxin (18 ) and zexbrevin (17 ) have been correlated with orizabin and ciliarin, it has been suggested that the stereochemistry of ester side chain in these compounds should also be revised. Besides these, some correlation attempts have been described which though not leading to the desired goal gave compounds which appeared to be chemically interesting. The third part of the thesis describes the experiments aimed at synthesizing vernolepin (39) from cynaropicrin(40) and tagitinin-C(3). The behaviour of the epoxides with different Lewis acids and mineral acids have been studied which while not leading to the desired rearrangement paves a way for further designing of the experiments to synthesize vernolepin (39).