Highly enantioselective ylide-mediated synthesis of terminal epoxides.

Highly enantioselective ylide-mediated synthesis of terminal epoxidesw

The importance of chiral epoxides as synthetic building blocks in asymmetric synthesis is extremely difficult to overstate. While the highly enantioselective Sharpless, and JacobsenKatsuki, protocols for the epoxidation of internal alkenes are nowmature technologies of inestimable value, the conversion of terminal alkenes to enantioenriched 1-oxiranes has proven a considerably more difficult pr...

Urea derivatives are highly active catalysts for the base-mediated generation of terminal epoxides from aldehydes and trimethylsulfonium iodide.

N,N'-Diarylureas have been shown to efficiently catalyse sulfonium ylide-mediated aldehyde epoxidation reactions for the first time. These processes are of broad scope and can be coupled with a subsequent Cu(II) ion-catalysed Meinwald rearrangement to give an efficient and convenient protocol for aldehyde homologation without intermediate purification.

Sulfur-ylide-mediated synthesis of functionalized and trisubstituted epoxides with high enantioselectivity; application to the synthesis of CDP-840.

A diastereoselective and concise synthesis of functionalised vinyl epoxides with a Morita-Baylis-Hillman backbone.

A highly diastereoselective organocatalytic synthesis of unique functionalised vinyl epoxides, displaying a Morita-Baylis-Hillman backbone, has been developed by means of an user friendly sulfonium ylide epoxidation of aldehydes from a readily available alpha-(bromomethyl)acrylamide derivative. The first result in the asymmetric version is discussed.

Stereoselective synthesis of three-membered ring compounds via ylide routes

Three types of small ring compounds (epoxides, aziridines and cyclopropanes) can be synthesized stereoselectively via ylide route. Among them, the stereochemistry of vinyloxiranes, vinylaziridines, cyclopropylesters, amides and ketones can be tuned by the choice of reaction conditions and ylides with varying heteroatoms and ligands. Optically active epoxides and acetylenylaziridines can be prep...