1 3 Dipolar cycloaddition based synthesis of Spiropyrrolidinones and Spiropyrrolidinediones

Abstract

Spirocyclic architecture is one of most privileged structural motifs newlinefound in numerous natural products and synthetic pharmaceuticals. Because newlineof their potent biological and pharmaceutical properties, different newlinemethodologies have been developed to construct spirocyclic architectures. newlineStill the construction of heteroatom incorporated spirocyclics remains a newlineformidable challenge. In this context, in the thesis entitled 1,3-DIPOLAR newlineCYCLOADDITION BASED SYNTHESIS OF SPIROPYRROLIDINONES AND newlineSPIROPYRROLIDINEDIONES we describe our attempts to utilize 1,3- newlinedipolar cycloaddition reaction for the synthesis of novel spiropyrrolidinones newlineand spiropyrrolidinediones using sterically hindered fluorenyl nitrones and newline1,1-disubstituted allenes precursors. newlineThe thesis is divided into four chapters. First chapter of the thesis newlinegives a general introduction to 1,3- dipolar cycloaddition, 1,3-dipoles, newlinedipolarophiles and related compounds. The introductory section gives more newlineimportance to the role of 1,3-dipolar cycloaddition for the synthesis of newlinespiroheterocyclics and reactions of 1,3-dipole, nitrones with various newlinedipolarophiles. Furthermore, importance of spiroheterocyclic compounds in newlinethe field of pharmaceutical chemistry is also discussed in this chapter. newlineThe second chapter discusses the synthesis of 1,3-dipoles fluorenyl newlinenitrones and dipolarophile allene. We selected a 1,1-disubstituted allene newlinefor the cycloaddition reactions. This chapter also illustrates the importance newlineof nitrones. The initial section of the third chapter includes the literature newlinesurvey of reactions of nitrones with allenes. The third chapter describes the synthesis of spiropyrrolidinones via newlinethe reactions of fluorenyl nitrones with 1,1-disubstituted allene through a newlinecycloaddition-sigmatropic shift sequence. Role of polarity of solvents, newlinetemperature and reaction time on cycloaddition reaction was examined in newlinedetail to unravel optimal conditions for the generation of newlinespiropyrrolidinones.