A Novel Approach to Diastereo and Enantio Selective Claisen Rearrangement Installation of All Carbon Quaternary Stereocenter in Acyclic System

Abstract

Organic molecules having all-carbon quaternary stereocenters are found in many natural newlineproducts and typically show unique bioactivities due to the rigid framework of threedimensional newlinestructure. Hence, the efficient and selective construction of all-carbon quaternary newlinestereocenters has attracted synthetic community the most. In the last few decades, various newlinemethodologies have been developed for the construction of the all-carbon quaternary newlinestereogenic center in an acyclic system. Furthermore, with an increase in structural complexity newline(i.e., the consecutive stereocenters out of which one is a quaternary stereocenter) and control newlineof stereoselectivity is still an intricate task in organic synthesis. In particular, methods like newlineasymmetric allylic alkylation, asymmetric conjugate addition, desymmetrization, and newlinerearrangement process are used to construct all-carbon quaternary stereocenter along with newlinecontiguous tertiary stereocenter in acyclic systems. However, limited structural diversities, the newlinecost of ligands/catalysts, and the stereochemical outcome are the major constraints of these newlinemethods. Therefore, new alternate efficient methods to incorporate vicinal all-carbon newlinequaternary and tertiary centers in acyclic systems become an inevitability of the moment. One newlinesuch method is Claisen rearrangement process, which poses an inherent diastereoselective newlinetransition state as well as atom economy. The advantages of this class of reaction include the newlineuse of easily accessible chiral auxiliary containing starting materials to provide the desired newlineenantioselectivity. newlineIn recent years several elegant efforts have been demarcated by several research groups toward newlinethe construction of all-carbon quaternary and tertiary stereocenters in 1,2-relationship in newlineacyclic carbon framework. The use of organocatalysts, dual catalysts, and the unique newlinefunctionality of the resulting products are the main focuses of Claisen rearrangement. Chiral newlineauxiliary mediated Claisen rearrangement starting from simple accessible newline