DOMINO C-H FUNCTIONALISATION OF OXINDOLE, INDOLE, PHENOL, FLUORENE & ITS APPLICATION TOWARDS CYCLOPROPANATION

Abstract

The work presented in this thesis is related to organic synthesis and the development of methods for the construction of carbon-carbon (C-C) bonds using domino C-H functionalization of oxindole, indole, phenols and fluorene. The key points presented in the thesis include (i) domino remote C-H functionalization (C-6 position) and C3-indolylation of peroxyoxindole: In this method, remote C-H functionalization at the C-6 position of oxindole was taken place. One of the highlighted reactions in this method is the skeletal rearrangement of 3-phenyl peroxyoxindole. It also involves the biologically important trinsindoline derivatives synthesis. (ii) Regiospecific coupling of phenol: The thesis discussed the diverse reaction of peroxyoxindole with phenol catalyzed by Lewis acids. Depending upon the catalyst nature, peroxyoxindoles undergo sequential rearrangement or direct elimination of peroxide followed by regiospecific coupling with phenol to afford heterocyclic scaffolds. These compounds may have potential applications in the field of medicine and drug discovery due to their heterocyclic nature. (iii) Selective alkylation/alkenylation of 9H-fluorene using borrowing hydrogen concept: The thesis covers the selective alkylation of 9H-fluorene by borrowing hydrogen catalysis using alcohol. Whereas, secondary alcohol furnished the 9-alkylidene-9H-fluorene as a major product. (iv) Application of alkyl/alkenyl-9H-fluorene towards hydroxylation and cyclopropanation: This thesis also describes the C-H hydroxylation of fluorene using atmospheric air as an oxygen source. Furthermore, the synthesized alkene was used for the cyclopropane ring synthesis using a continuous flow module. Overall, the thesis presents a comprehensive exploration of various methods for C-H functionalization of indole, phenols and fluorene derivatives using domino rearrangement and borrowing hydrogen catalysis. Additionally, highly strained cyclopropanes are synthesized using continuous flow techniques.