Epoxidation S -

Prepared by epoxidation of styrene with per-oxyelhanoic acid. Reactions are similar to those of aliphatic epoxides (s e, e.g. ethylene oxide). Reacts with alcohols to give mono-ethers, e g. PhCH(0Me)CH20H. Phenols give resins. 

The preparation of novel phase transfer catalysts and their application in solving synthetic problems are well documented(l). Compounds such as quaternary ammonium and phosphonium salts, phosphoramides, crown ethers, cryptands, and open-chain polyethers promote a variety of anionic reactions. These include alkylations(2), carbene reactions (3), ylide reactions(4), epoxidations(S), polymerizations(6), reductions(7), oxidations(8), eliminations(9), and displacement reactions(10) to name only a few. The unique activity of a particular catalyst rests in its ability to transport the ion across a phase boundary. This boundary is normally one which separates two immiscible liquids in a biphasic liquid-liquid reaction system. 

Physical and Chemical Properties of Heptachlor and Heptachlor Epoxide s... 

Peter Lacouture, Associate Director, Clinical Research, The Purdue Frederick Company, Norwalk, Connecticut Dr. Fumio Matsumura, Associate Director, Toxic Substances Program, Institute of Toxicology and Environmental Health, University of California, Davis, California Dr. Frederick Oehme, Director, Comparative Toxicology Laboratories, Kansas State University, Manhattan, Kansas and Dr. Jack Radomski, Private Consultant, Jonesport, Maine. These experts collectively have knowledge of heptachlor and heptachlor epoxide s physical and chemical properties, toxicokinetics, key health end points, mechanisms of action, human and animal exposure, and quantification of risk to humans. All reviewers were selected in conformity with the conditions for peer review specified in Section 104(i)(13) of the Comprehensive Environmental Response, Compensation, and Liability Act, as amended. 

The non-subtype-selective p-AR radioligand (S)-p F]fluoroethylcarazolol 8 is prepared by reaction of 2-[ F]fluoroethyl amine with the corresponding epoxide (S)-4-(2,3-epoxypropoxy)carbazole (Fig. 13). 

Scheme 2.2.7.16 Synthesis of nitrile (R)-30 through intermediate epoxide (S)-29a.

To attain the requirements of an epoxy matrix utilized in filament-wound C-fiber-epoxy composites we have considered the characteristics required of the amine curing agent molecule. To ensure long gel times at 23 °C requires that the primary amine-epoxide (P.A.-E) reaction rate is considerably greater than the rate of the secondary amine-epoxide (S. A.-E) reaction, and that the S.A. reaction does not occur at low temperatures. Furthermore, to attain low 23 °Cr s and low post-cure temperatures... 

Another type of sulfide catalyst, thiazolidine derivatives of type 220, were designed by the Koskinen group with the aid of molecular modeling [221]. In the model reaction the thiazolidine 220 catalyzed the formation of the trans epoxide (S,S)-trans-202a highly enantioselectively (90% ee) although the yield (16%) was low (Scheme 6.98). 

Fpr most substitution reactions of epoxides, then, regioselectivity is much higher if you give in to the epoxide s desire to open at the less substituted end, and enhance it with a strong nucleophile under basic conditions. 

The regiochemistry of acid-catalyzed ring opening depends on the epoxide s structure, and a mixture of products is usually formed. When both epoxide carbon atoms arc cither primary or secondary attack of the nucleophile occurs primarily at the less highly substituted site. When one of the epoxide carbon atoms is tertiary,however nucleophilic attack occurs primarily at the more highly substituted site. Thus, L,2-epoxypropane jeac t with HCl to give primarily l-chloro-2-propanol, but 2-methyl 1,2-cpoxypropane gives 2-chloro-2-methyl-l-propanol as the major product. 

Eq. 612), Similarly, attempted epoxidation S-proponyl-p Oreeol proved lUkBueceeefu] because the intermediate epoxide aufi ed ready roarrangomeot in the opoxidadon moditim, givmg 2,5-dimethylbenz>0 >... 

As a consequence of the target epoxide s specific stereochemical formation requirements, the aforementioned anhydrosugar conformation forces the hexose out of the stable C4 conformation into the Hq conformation, which is higher in energy and easily attacked by nucleophiles, thus enabling a variety of applications. This particular property of high chenucal reactivity... 

System Athene epoxidation S NS Alkane hydroxylation S NS Arene hydroxylation NIH shift Athene ketonization R s. 

In the course of the synthesis of the potent HIV-protease inhibitor Ro 31-8959 [74], a simple entry to epoxide (S,S)-84 (Fig. 25) was needed. Of the many attempted routes, the one based on Sharpless catalytic epoxidation, reported in Fig. 25, proved to be very successful [75]. 

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