Metal-catalyzed asymmetric reactions enabled by organic peroxides

As a class of multifunctional reagents, organic peroxides play vital roles in the chemical industry, pharmaceutical synthesis and polymerization reactions. Metal-catalyzed asymmetric catalysis has emerged as one of the most straightforward and efficient strategies to construct enantioenriched molecules, and an increasing number of metal-catalyzed asymmetric reactions enabled by organic peroxides have been disclosed by researchers in recent years. Despite remarkable progress, the types of asymmetric reactions facilitated by organic peroxides remain limited and the catalysis systems need to be further broadened. To the best of our knowledge, there is still no review devoted to summarizing the reactions from this perspective. In this review, we will endeavor to highlight the advances in metal-catalyzed asymmetric reactions enabled by organic peroxides. We hope that this survey will summarize the functions of organic peroxides in catalytic reactions, improve the understanding of these compounds and inspire future developments in this area.

Water, an Essential Element for a ZnII -Catalyzed Asymmetric Quinone Diels-Alder Reaction: Multi-Selective Construction of Highly Functionalized cis-Decalins

A Zn^II complex of a C₂ -chiral bisamidine-type sp² N bidentate ligand (L_R ) possessing two dioxolane rings at both ends catalyzes a highly efficient quinone asymmetric Diels-Alder reaction (qADA) between o-alkoxy-p-benzoquinones and 1-alkoxy-1,3-butadienes to construct highly functionalized chiral cis-decalins, proceeding in up to a >99:1 enantiomer ratio with a high generality in the presence of H₂ O (H₂ O:Zn^II =4-6:1). In the absence of water, little reaction occurs. The loading amount of the chiral ligand can be minimized to 0.02 mol % with a higher Zn/L_R ratio. This first success is ascribed to a supramolecular 3D arrangement of substrates, in which two protons of an "H₂ O-Zn^II " reactive species make a linear hydrogen bond network with a dioxolane oxygen atom and one-point-binding diene; the Zn^II atom captures the electron-accepting two-points-binding quinone fixed on the other dioxolane oxygen atom via an n-π* attractive interaction. The mechanisms has been supported by ¹ H NMR study, kinetics, X-ray crystallographic analyses of the related ZnL_R complexes, and ligand and substrate structure-reactivity-selectivity relationship.