OsO4⋅Streptavidin: A Tunable Hybrid Catalyst for the Enantioselective cis‐Dihydroxylation of Olefins

Abstract

Enzymatic and homogeneous catalysis have evolved independently to address the challenges in the synthesis of enantiopure products. With the aim of complementing these fields, artificial metalloenzymes, which combine the structural diversity of biocatalysts with the wealth of metal-catalyzed reactions, have attracted increasing attention. [1] In homogeneous catalysis the cis-selective, OsO4-dependent asymmetric dihydroxylation (AD) of olefins ranks among the most powerful methods for the synthesis of vicinal diols. Ligands for homogeneous catalysis have been largely developed by Sharpless and co-workers, and are, with few exceptions, almost exclusively based on quinidine or quinine derivatives. [2] Although most classes of prochiral olefins are dihydroxylated with good activity and selectivity, the cissubstituted olefins are problematic. Nature relies on nonheme iron dioxygenases such as naphthalene dioxygenase (NDO) to perform a related reaction. These enzymes display broad substrate scope. [3] It is believed that both the OsO4- and NDO-catalyzed dihydroxylations proceed by an outer sphere [3+2] mechanism in which the substrate is not bound to the