Asymmetric epoxidation catalyzed by N-aryl-substituted oxazolidinone-containing ketones: further evidence for electronic effects.

[reaction: see text] Ketones containing N-aryl-substituted oxazolidinones have been prepared and investigated for the epoxidation of cis-beta-methylstyrene, styrene, and 1-phenylcyclohexene. The attractive interaction between the phenyl group of the olefin and the oxazolidinone of the catalyst is enhanced by introducing an electron-withdrawing group onto the N-phenyl group of the catalyst. The information obtained gives a better understanding of the ketone-catalyzed epoxidation. In addition, the easy preparation of some of the ketones makes them good candidates for practical use.

A New Dyad Based on C(60) and a Conjugated Dimethylaniline-Substituted Dithienylethylene Donor.

A facile synthesis of the title compound is described, and its optical and electrochemical properties are discussed.

Chemistry of C84 : Separation of Three Constitutional Isomers and Optical Resolution of D2 -C84 by Using the "Bingel-Retro-Bingel" Strategy.

The pure enantiomers of D2 -C84 as well as a third constitutional isomer of this higher fullerene were produced by a retro-Bingel reaction on the first organic derivatives of C84 (see scheme). These derivatives were synthesized by Bingel cyclopropenation of C84 , separated, and unambiguously structurally characterized.

An N-aryl-substituted oxazolidinone-containing ketone-catalyzed asymmetric epoxidation with hydrogen peroxide as the primary oxidant.

Asymmetric epoxidation of various olefins with an N-aryl-substituted oxazolidinone-containing ketone as catalyst and hydrogen peroxide as the primary oxidant has been investigated, and up to 96% ee was obtained.

Effective asymmetric epoxidation of styrenes by chiral dioxirane.

High enantioselectivity (80-92% enantiomeric excess (ee)) has been obtained for the epoxidation of various styrenes using an easily prepared ketone (4) catalyst.

Chiral Lewis acid catalyzed resolution of racemic enol ester epoxides. Conversion of both enantiomers of an enol ester epoxide to the same enantiomer of acyloxy ketone.

This paper describes an efficient kinetic resolution of racemic enol ester epoxides via a chiral Lewis acid catalyzed rearrangement. Both enantiomerically enriched enol ester epoxides and alpha-acyloxy ketones can be obtained through this resolution. A positive nonlinear effect is observed in this process. By taking advantage of the mechanistic duality in acid-catalyzed enol ester epoxide rearrangement, we can completely convert a racemic enol ester epoxide into an enantiomerically enriched alpha-acyloxy ketone by treatment with a catalytic amount of a chiral Lewis acid followed by a catalytic amount of an achiral protic acid.

Designing new chiral ketone catalysts. Asymmetric epoxidation of cis-olefins and terminal olefins.

This paper describes a new class of chiral oxazolidinone ketone catalyst for asymmetric epoxidation. High ee values have been obtained for a number of cyclic and acyclic cis-olefins. The epoxidation was stereospecific with no isomerization observed in the epoxidation of acyclic systems. Encouragingly high ee values have also been obtained for a number of terminal olefins. Mechanistic studies show that electronic interactions play an important role in stereodifferentiation.

An improved synthesis of a ketone catalyst for asymmetric epoxidation of olefins.

An efficient synthesis of a ketone catalyst for asymmetric epoxidation of olefins from D-glucose in six steps is described.