Epoxidation from aldehydes

Epoxides from aldehydes, 46, 44 Equatorial alcohols, preparation by use of the lithium aluminum hydride-aluminum chloride reagent, 47, 19... 

Related Methods Section 124 (Epoxides from Aldehydes). 

The Formation of Epoxides from Aldehydes and Ketones (1 + 2)OC,CC-CKC/o-Methylene-addition... 

Related Methods Epoxides from Aldehydes (Section 124)... 

We could compare sulfonium ylids with the carbenoids we discussed in Chapter 40—both are nucleophilic carbon atoms carrying a leaving group, and both form three-membered rings by insertion into n bonds. Sulfonium ylids are therefore useful for making epoxides from aldehydes or ketones other ways you have met of making epoxides (Chapters 20 and 45) started with alkenes that might be made with phosphorus ylids. 

Diels-Alder additions in water. It also catalyzes aldehyde olefination with N2C(C02Et)2 and PPhs as oxygen sink. Its catalyzed decomposition of N2C(C02Et)2 leads to carbene transfer reactions allowing for the formation of epoxides from aldehydes and ketones, aziridines from imines and cyclopropanation. 

Corey-Chaykovsky epoxidation Preparation of epoxides from aldehydes and ketones. 102... 

Condensation with carbonyl compounds. Formation of epoxides from aldehydes by reaction with sulfonium ylides is subject to asymmetric induction. The latter species have been generated from 91, 92, and 93, and also those derived from monoterpenes, e.g., 94 " and 95.- Of course the ylides can be obtained in situ by deprotonation of sulfonium salts or copper-catalyzed decomposition of diazoalkanes (with the carbenoids trapped by the sulfides). 

A novel synthesis of epoxides from aldehydes and sulfur ylides has been reported this past year [94JA5973]. This reaction, which gives predominantly trans epoxides, proceeds through an interesting catalytic cycle in which the sulfur ylide is generated in situ from a diazo precursor, which is slowly added into a reaction medium containing catalytic rhodium(II) acetate and substoichiometric amounts of dimethyl sulfide. The use of a chiral sulfide produced observable (11%) enantioselectivity. 

Sulfonium ylids are therefore useful for making epoxides from aldehydes or ketones other ways you have met of making epoxides (Chapter 19) started with alkenes that might themselves be made with phosphorus ylids. 

In 2008, Connon and coworkers reported a base-mediated protocol for the S3mthesis of terminal epoxides from aldehydes and trimethylsulfonium iodide utilising 5 mol% of urea analogue 9. Electron-rich and electron-deficient aromatic aldehydes were well tolerated providing the corresponding products in moderate to high yields. In the case of cycloheigrl carboxaldehyde, an increase in the reaction time was required. It has to be... 

Some of the methods listed in section 132 (Ethers and Epoxides from Ketones) may also be applied to the preparation of ethers and epoxides from aldehydes... 

In 1990, Huang et al. reported the synthesis of vinyl epoxides from aldehydes catalyzed by diisobutyl telluride (237). The ditelluride works with a variety of different aldehydes. An example is shown below (Schane 7.53) [198]. 

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