Epoxidation compounds

Unlike most ethers epoxides (compounds m which the C—O—C unit forms a three membered ring) are very reactive substances The principles of nucleophilic sub stitution are important m understanding the preparation and properties of epoxides... 

With allyl alcohol, carbon tetrachloride forms a complex mixture of epoxide compounds in C4 that detonate during their distillation. One of these epoxides is thought to be the following ... 

An inhibitor during drilling and servicing of oil and gas wells is a condensate of aminopyrazine and an epoxide compound, such as the glycidyl ether of a mixture of Cn to C14 alkanols [604]. 

Zheng J. Screening of active anti-inflammatory, immunosuppressive and anti-fertility components of Tripterygium wildfordii III. A comparison of the anti-inflammatory and immunosuppressive activities of 7 diterpene lactones epoxides compounds in vivo. Zhongguo Yixue Kexueyuan Xuebao 1991 13 391-397. 

The existence of isomeric polycyclic aromatic diol epoxide compounds provides rich opportunities for attempting to correlate biological activities with the physico-chemical reaction mechanisms, and conformational and biochemical properties of the covalent DNA adduct8 which are formed. 

The wide scope application of this transformation arises not only from the utility of epoxide compounds but also from the subsequent regiocontrolled and stereocontrolled nucleophilic substitution (ring-opening) reactions of the derived epoxy alcohol. These, through further functionalization, allow access to an impressive array of target molecules in enantiomerically pure form. 

The coupling product 177 is subjected to epoxidation to give epoxide compound 178 on which the C-l hydroxyl group will be generated via catalytic hydrogenation. After the dihydroxyl groups of the hydrogenation product 179 have been protected with cyclic carbonate, the C=C double bond between C-l2... 

Via Asymmetric Epoxidation and Related Reactions. Denis et al.35 synthesized the taxol side chain derivative via Sharpless epoxidation. Starting from cw-cinnamyl alcohol, the corresponding epoxide compound was prepared with 76-80% ee. Subsequent azide ring opening gives a product that possesses the side chain skeleton (Scheme 7-78). 

Deng and Jacobsen38 used Mn-salen complex for the asymmetric epox-idation of ethyl cinnamate. Over 95% ee was obtained for the epoxide compound (Scheme 7-81). 

Commerqon et al.40 developed a method based on an Evans-type auxiliary-controlled aldol reaction. Subsequent treatment of the aldol product with base produced the standard epoxide compound for the asymmetric synthesis of the taxol side chain (Scheme 7-84). 

The difference between the two catalysts is even more manifest in the profiles of the yield of epoxidized compounds after 24 h (Fig. 12.2). Only over Ti-MCM-41... 

Cyclic voltammetry, kinetic studies, and DFT calculations using a BP functional and the TZVP basis set showed that the major pathway of the non-regiospeciflc zinc-reduced titanocene-mediated ring opening of epoxides was initiated by a titanium dimer-epoxide compound that reacted in a rate-determining electron transfer mechanism 25 The calculations showed that the transition state is early so the stereoselectivity is determined by steric effects rather than by the stability of intermediate radicals. This was confirmed by studies with more sterically crowded catalysts. 

Lithium aluminum hydride reduces the carboxylic acid to the corresponding primary alcohol, compound E. Treatment of the vicinal chlorohydrin with base results in formation of an epoxide, compound F. 

Treatment of the alkene with m-chloroperoxybenzoic acid produces an epoxide, compound B. 

To explain the mechanism of N2 oxidative fixation with hydrogen peroxide, the fact should be applied that the stage mechanism of unsaturated compound epoxidation includes elementary reactions involving HO and R02 free. These radicals are able to break the O—O bond with further addition of oxygen to epoxidized compound. 

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