Cr-salen mediated asymmetric epoxidation of alkenes: Rational complex design and substrate scope of catalyst

Clarke, Eoin F.; McGarrigle, Eoghan M.; Gilheany, Declan G.

doi:10.3998/ark.5550190.0006.104

Cited by 2 publications

(1 citation statement)

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“…A ground-breaking achievement in this area occurred in 1980 with the enantioselective epoxidation of allylic alcohols by tert -butyl hydroperoxide (TBHP), titanium tetraisopropoxide, and diethyl tartrate . The benchmark reaction reported by Katsuki and Sharpless was followed by broad application of asymmetric epoxidation to alkenes using transition metal catalysis, including metal–salen complexes based on manganese, − chromium, − and ruthenium. , The oxidants employed in these reactions were alkyl hydroperoxides, iodosylbenzene, sodium hypochlorite, and oxones, all of which result in low atom efficiency. An important advance was made in 2005 by Katsuki who described a highly enantioselective epoxidation of nonfunctionalized conjugated olefins catalyzed by di-μ-oxo-titanium trans -1,2-diaminocyclohexane-salalen catalyst 120 containing a semireduced salen ligand (Scheme ).…”

Section: Asymmetric Reactions Catalyzed By Salen–metal Complexesmentioning

confidence: 99%

Asymmetric Catalysis Using Chiral Salen–Metal Complexes: Recent Advances

2019

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Chiral salen−metal complexes are among the most versatile asymmetric catalysts and have found utility in fields ranging from materials chemistry to organic synthesis. These complexes are capable of inducing chirality in products formed from a wide variety of chemical processes, often with close to perfect stereoinduction. Salen ligands are tunable for steric as well as electronic properties, and their ability to coordinate a large number of metals gives the derived chiral salen−metal complex very broad utility in asymmetric catalysis. This review primarily summarizes developments in chiral salen−metal catalysis over the last two decades with particular emphasis on those applications of importance in asymmetric synthesis. CONTENTS 1. Introduction and Background 9382 2. Chiral Salen Ligands: Synthesis and Metalation 9382 3. Stereostructural Properties of Chiral Salen−Metal Complexes 9383 4.

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