Sharpless olefin synthesis

Olefin synthesis from the i yn-oxidative elimination of o-nitrophenyl selenides, whieh may be prepared using o-nitrophenyl selenoeyanate and BusP, among other methods. 

Medert, K. Pettit, G. R. Vogel, P. Helv. Chim. Acta 2004, 87, 1493—1507. 

Cardona, L. Collado, A. M. Garcia, B. Morcillo, V. Pedro, J. R. J. Org. Chem. 2004, 69, 7294—7302. The authors observed the concurrent epoxidation of a tri-subsituted olefin, possibly by the o-nitrophenylselenic acid via an intramolecular process. 

A ame Reactions A Collection of Detailed Mechanisms and Synthetic Applications, DOI 10.1007/978-3-319-03979-4 251, Springer International Publishing Switzerland 2014 

Name Reactions, si., DOI 10.1007/978-3-642-01053-8 235, Springer-Verlag Berlin Heidelberg 2009 

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A. Krief, A.-M. Laval, Ortho-Nitrophenyl Selenocyanate, a Valuable Reagent in Organic Synthesis Application to One of the Most Powerful Routes to Terminal Olefins from Primary-Alcohols (The Grieco-Sharpless Olefination Reaction) and to the Regioselective Isomerization of Allyl Alcohols), ... 

A. Krief and A.-M. Laval, u-Nitrophenyl selenocyanate, a valuable reagent in organic synthesis Application to one of the most powerful routes to terminal olefins from primary-alcohols (the Grieco-Sharpless olefination reaction) and to the regioselective isomerization of allyl alcohols, Bull. Soc. Chim. Fr. 1997,13, 869-874. 

Natural product synthesis and medicinal chemistry exist in a symbiotic relationship with the development of synthesis methodology. Noy-ori s asymmetric hydrogenations, Sharpless olefin oxidations, Grubbs olefin metathesis, Buchwald-Hartwig couplings and Jacobsen s hydrolytic kinetic resolution are illustrious examples with many practical applications. The key to the success of the above-mentioned reactions is that they have provided reliable shortcuts to more traditional synthetic... 

Sharpless, K. B., Flood, T. C. Direct deoxygenation of vicinal diols with tungsten(IV). New olefin synthesis. J. Chem. Soc., Chem. Common. 1972,370-371. 

CLIVE-REICH-SHARPLESS Olefination Organoselenium compounds in synthesis of terminal olefins, unsaturated ketones... 

Olefin synthesis. The preparation of olefins by decomposition of alkyl phenyl selenoxides (Diphenyl diselenide, 5, 272-276) is very useful, except in the case of primary alkyl phenyl selenoxides, which usually give low yields of terminal olefins on decomposition. However, the presence of electron-withdrawing substituents on the benzene ring increases both the rate of elimination and the yield of olefins. In instances where use of diphenyl diselenide results in low yields. Sharpless and Young recommend use of o-nitrophenyl selenocyanate (1) or 4,4 -dichlorodiphenyl diselenide, both of which are converted into the corresponding ArSe Na" reagents on reduction with sodium borohydride in ethanol. 

Grieco, P. A. Gilman, S. Nishizawa, M. Organoselenium Chemistry. A Facile One-Step Synthesis of Alkyl Aryl Selenides from Alcohols /. Or. Chem. 1976, 41, 1485-1486. Sharpless, K. B. Young, M. W. Olefin Synthesis. Rate Enhancement of the Elimination of Alkyl Aryl Selenoxides by Electron-Withdrawing Substituents / Or . Chem. 1975, 40, 947-949. 

The past thirty years have witnessed great advances in the selective synthesis of epoxides, and numerous regio-, chemo-, enantio-, and diastereoselective methods have been developed. Discovered in 1980, the Katsuki-Sharpless catalytic asymmetric epoxidation of allylic alcohols, in which a catalyst for the first time demonstrated both high selectivity and substrate promiscuity, was the first practical entry into the world of chiral 2,3-epoxy alcohols [10, 11]. Asymmetric catalysis of the epoxidation of unfunctionalized olefins through the use of Jacobsen s chiral [(sale-i i) Mi iln] [12] or Shi s chiral ketones [13] as oxidants is also well established. Catalytic asymmetric epoxidations have been comprehensively reviewed [14, 15]. 

Optically active epoxides are important building blocks in asymmetric synthesis of natural products and biologically active compounds. Therefore, enantio-selective epoxidation of olefins has been a subject of intensive research in the last years. The Sharpless [56] and Jacobsen [129] epoxidations are, to date, the most efficient metal-catalyzed asymmetric oxidation of olefins with broad synthetic scope. Oxidative enzymes have also been successfully utilized for the synthesis of optically active epoxides. Among the peroxidases, only CPO accepts a broad spectrum of olefinic substrates for enantioselective epoxidation (Eq. 6), as shown in Table 8. 

Asymmetric epoxidation of olefins is an effective approach for the synthesis of enan-tiomerically enriched epoxides. A variety of efficient methods have been developed [1, 2], including Sharpless epoxidation of allylic alcohols [3, 4], metal-catalyzed epoxidation of unfunctionalized olefins [5-10], and nucleophilic epoxidation of electron-deficient olefins [11-14], Dioxiranes and oxazirdinium salts have been proven to be effective oxidation reagents [15-21], Chiral dioxiranes [22-28] and oxaziridinium salts [19] generated in situ with Oxone from ketones and iminium salts, respectively, have been extensively investigated in numerous laboratories and have been shown to be useful toward the asymmetric epoxidation of alkenes. In these epoxidation reactions, only a catalytic amount of ketone or iminium salt is required since they are regenerated upon epoxidation of alkenes (Scheme 1). 

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