Recent advances in metal-free catalytic enantioselective higher-order cycloadditions

Abstract

Higher-order cycloadditions (HOCs) present notable benefits for the synthesis of complex molecules, particularly those featuring medium size and multiple rings. The research on HOCs has experienced remarkable advancements since the influential exchange between Woodward and Hoffmann. In recent decades, significant progress has been achieved in enantioselective metal-free catalytic HOCs. These methodologies have facilitated the regulation of peri- and enantioselectivity during ring formation. With the diversification of activation modes, the variety of intermediates used in HOCs has also been greatly expanded. This review focuses on strategies for metal-free catalytic construction of chiral frameworks. To our knowledge, there are still many unknowns to be discovered in enantioselective HOCs.