Asymmetric Cycloaddition and Cyclization Reactions Catalyzed by Chiral N,N′-Dioxide–Metal Complexes

TLDR: Recent studies on asymmetric cycloadditions between various dienophiles and dienes, dipoles and dipolarophiles, and cascade cyclizations catalyzed by chiral N,N'-dioxide-metal complexes reveal the importance of tunability and compatibility of the ligands and metal precursors for achieving high stereoinduction and activity.

Abstract: ConspectusCatalytic asymmetric cycloadditions and cascade cyclizations are a major focus for the enantioselective construction of chiral carbo- and heterocycles. A number of chiral Lewis acids and organocatalysts have been designed for such reactions. The development of broadly applicable catalysts bearing novel chiral backbones to meet the demands of various applications is an ongoing challenge. Approximately 10 years ago, we introduced a group of conformationally flexible C2-symmetric N,N′-dioxide amide compounds, which represent a new class of privileged ligands. The coordination of the four oxygens of a chiral N,N′-dioxide around a central metal generates an octahedral tricyclometalated Lewis acid catalyst that can carry out various enantioselective reactions. In this Account, we summarize our recent studies on asymmetric cycloadditions between various dienophiles and dienes, dipoles and dipolarophiles, and cascade cyclizations catalyzed by chiral N,N′-dioxide–metal complexes. In principle, these uniq...