posted on 2013-05-01, 00:00authored byOlga Lifchits, Manuel Mahlau, Corinna M. Reisinger, Anna Lee, Christophe Farès, Iakov Polyak, Gopinadhanpillai Gopakumar, Walter Thiel, Benjamin List
Using cinchona alkaloid-derived primary
amines as catalysts and
aqueous hydrogen peroxide as the oxidant, we have developed highly
enantioselective Weitz–Scheffer-type epoxidation and hydroperoxidation
reactions of α,β-unsaturated carbonyl compounds (up to
99.5:0.5 er). In this article, we present our full studies on this
family of reactions, employing acyclic enones, 5–15-membered
cyclic enones, and α-branched enals as substrates. In addition
to an expanded scope, synthetic applications of the products are presented.
We also report detailed mechanistic investigations of the catalytic
intermediates, structure–activity relationships of the cinchona
amine catalyst, and rationalization of the absolute stereoselectivity
by NMR spectroscopic studies and DFT calculations.