Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Stereoselective Epoxide Ring-Opening Reactions

Ibuka, T., Nakai, K., Akaji, M., Tamamura, H., Fujii, N., Yamamoto, Y. An aza-Payne rearrangement-epoxide ring opening reaction of 2-aziridinemethanols in a one-pot manner a regio- and stereoselective synthetic route to diastereomerically pure N-protected 1,2-amino alcohols. Tetrahedron 1996, 52, 11739-11752. [Pg.649]

Epoxides are regio- and stereoselectively transformed into fluorohydrins by silicon tetrafluoride m the presence of a Lewis base, such as diisopropyleth-ylamme and, m certain instances, water or tetrabutylammonium fluoride The reactions proceed under very mild conditions (0 to 20 C in 1,2-diohloroethane or diethyl ether) and are highly chemoselective alkenes, ethers, long-chain internal oxiranes, and carbon-silicon bonds remain intact The stereochemical outcome of the epoxide ring opening with silicon tetrafluoride depends on an additive used, without addition of water or a quaternary ammonium fluoride, as fluorohydrins are formed, whereas m the presence of these additives, only anti opening leading to trans isomers is observed [17, 18] (Table 2)... [Pg.204]

The asymmetric oxidation of organic compounds, especially the epoxidation, dihydroxylation, aminohydroxylation, aziridination, and related reactions have been extensively studied and found widespread applications in the asymmetric synthesis of many important compounds. Like many other asymmetric reactions discussed in other chapters of this book, oxidation systems have been developed and extended steadily over the years in order to attain high stereoselectivity. This chapter on oxidation is organized into several key topics. The first section covers the formation of epoxides from allylic alcohols or their derivatives and the corresponding ring-opening reactions of the thus formed 2,3-epoxy alcohols. The second part deals with dihydroxylation reactions, which can provide diols from olefins. The third section delineates the recently discovered aminohydroxylation of olefins. The fourth topic involves the oxidation of unfunc-tionalized olefins. The chapter ends with a discussion of the oxidation of eno-lates and asymmetric aziridination reactions. [Pg.195]

Spino and Frechette reported the synthesis of non-racemic allenic alcohol 168 by a combination of Shi s asymmetric epoxidation of 166 and its organocopper-mediat-ed ring-opening reaction (Scheme 4.43) [74]. Reduction of the ethynyl epoxide 169 with DIBAL-H stereoselectively gave the allenic alcohol 170, which was converted to mimulaxanthin 171 (Scheme 4.44) [75] (cf. Section 18.2.2). The DIBAL-H reduction was also applied in the conversion of 173 to the allene 174, which was a synthetic intermediate for peridinine 175 (Scheme 4.45) [76], The SN2 reduction of ethynyl epoxide 176 with DIBAL-H gave 177 (Scheme 4.46) [77]. [Pg.160]

Keywords epoxide, stereoselective, addition, ring opening, gas-solid reaction... [Pg.353]

Until now, three main F-C transformations have been used for catalytic stereoselective formation of benzylic carbon stereocenters - 1,2-addition of arenes to carbonyl (C=X, X O, NR) moieties, 1,4-addition of arenes to electron-deficient C-C double bonds, and ring-opening reaction of epoxides. [Pg.152]


See other pages where Stereoselective Epoxide Ring-Opening Reactions is mentioned: [Pg.216]    [Pg.216]    [Pg.322]    [Pg.65]    [Pg.110]    [Pg.183]    [Pg.255]    [Pg.175]    [Pg.266]    [Pg.416]    [Pg.35]    [Pg.155]    [Pg.159]    [Pg.425]    [Pg.97]    [Pg.206]    [Pg.52]    [Pg.160]    [Pg.180]    [Pg.702]    [Pg.141]    [Pg.35]    [Pg.204]    [Pg.160]    [Pg.100]    [Pg.469]    [Pg.163]    [Pg.81]    [Pg.532]    [Pg.470]    [Pg.470]    [Pg.420]    [Pg.186]    [Pg.267]    [Pg.324]    [Pg.97]    [Pg.92]    [Pg.506]    [Pg.1709]    [Pg.418]    [Pg.105]   


SEARCH



Epoxidation stereoselectively

Epoxidation stereoselectivity

Epoxidation/ring-opening

Epoxide openings

Epoxide reaction

Epoxide ring openings

Epoxides reactions

Epoxides ring opening

Epoxides stereoselectivity

Reaction stereoselectivity

Reactions epoxidation

Ring epoxides

Ring opening reactions

Ring opening reactions epoxides

Ring opening stereoselectivity

Ring stereoselectivity

Stereoselective epoxidations

Stereoselective reactions

Stereoselective ring opening

© 2024 chempedia.info