Diastereoselective construction of structurally diverse spirooxindoles via annulation of morita baylis hillman adducts of isatin

Abstract

The carbon 8722 carbon bond forming reactions have always remained as one of the most indispensable reactions in organic synthesis Among various carbon 8722 carbon bond forming reactions the Morita 8722 Baylis 8722 Hillman MBH reaction is one of the very useful and potential transformations with enormous synthetic utility The dense functionalities and versatile reactivity of Morita Baylis Hillman MBH adducts make them powerful precursors for building various carbocyclic heterocyclic and other important compounds of biological significance In recent the years isatin derived Morita Baylis Hillman MBH carbonates have emerged as versatile synthons for constructing multi functional spirooxindole scaffolds under organocatalytic conditions In this thesis novel uses of MBH carbonates of isatin have been explored for the efficient organocatalytic transformations to synthesize useful scaffolds such as spiroheterocycles Various interesting and useful spiroheterocycles such as bis spirooxindoles cyclopropyl spirooxindoles spirooxindole dihydofuran fused pyrazolones spirocyclopentadienes cyclopenetene spirooxindoles and spirooxindole dihydopyrrole fused pyrazolones have been synthesized by utilizing Morita Baylis Hillman carbonates of isatin under tertiary amine catalysis We have developed highly efficient organocatalytic 3 2 and 2 1 annulations between isatin derived Morita 8722 Baylis 8722 Hillman carbonate and 3 methyleneoxindoles to access bis spirooxindoles appended with cyclopentene and cyclopropane derivatives Later we explored the utility of cinchona derived chiral tertiary amine catalyst in the cycloaddition between isatin derived Morita 8722 Baylis 8722 Hillman adducts and pyrazolone 4 5 diones to construct enantiopure spirooxindole dihydrofuran fused pyrazolones scaffold We have successfully employed aurones and thioaurones as a suitable C2 synthon in 3 2 annulation with MBH carbonates of isatin to construct structurally diverse and multi functionalized sprio fused carbopentacyclic scaffold under suitable