SYNTHESIS OF DIENYNES AND ITS APPLICATIONS TO ACCESS COMPLEX MOLECULES

Abstract

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The content of the dissertation has been devided into four parts. Part-I illustrates overview on enynes and dienynes through C-C bond formation reactions. Further it also described importance and synthesis of diene aldehyde, alkyne aldehyde, enyne, dienyne derivatives and iodine mediated reactions in organic synthesis. Part-II is about an approach for the synthesis of functionalized unsymmetrical 1,3-butadiene-3-yne derivatives starting from β-halo styrene and phenyl acetylene derivatives in the presence of PdCl2 and CuI catalysts. Functional groups such as aldehyde, cyano and ester groups are well tolerated and afford the desired functionlized dienynes. Further, these 1,3-buta-diene-3-yne derivatives are utilized for the synthesis of novel trisubstituted pyridine derivatives. In Part-III, an efficient method for the synthesis of polysubstituted cyclopentene and cyclopenta[b]carbazole derivatives through the iodine promoted electrocyclization of substituted indoles and 4-Arylidene-3,6-diarylylhex-2-en-5-ynal derivatives is reported. Polysubstituted cyclopentene derivatives were furnished through 4π electrocyclization reactions with indole, 7-methylindole and 5-bromoindole as coupling partners. Whereas, cyclopenta[b]carbazole derivatives were produced via 6π electrocyclization in the case of methoxy (-OMe) substituted indoles. The methods reported are diastereo- and regioselectively proceeding under straightforward and mild conditions. Part-IV describes synthesis of fused bridgehead carbocycles from dimerization of unsymmetrical 1,3-butadiene-3-ynal derivatives via iodine mediated iso-Nazarov reaction. Bridgehead carbocyclic derivatives are produced as major products in the reaction, which involves the generation of new C-C bonds and new stereo centers. On the other hand,. The methods reported herein are diastereo- and regioselective and proceed under mild conditions.