Arsonium ylides in organic synthesis

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A multipolymer system for organocatalytic alcohol oxidation

A system involving two polymer-supported reagents for the selective and organocatalytic oxidation of alcohols to aldehydes or ketones has been developed in which both polymeric reagents can be recovered and reused. © The Royal Society of Chemistry 2005.postprin

The Mitsunobu reaction: Origin, mechanism, improvements, and applications

The Mitsunobu reaction is a widely used and versatile method for the dehydrative oxidation-reduction condensation of an acid/pronucleophile usually with a primary or secondary alcohol that requires the combination of a reducing phosphine reagent together with an oxidizing azo reagent. The utility of this reaction stems from the fact that it is generally highly stereoselective and occurs with inversion of the stereochemical configuration of the alcohol starting material. Furthermore, as carboxylic acids, phenols, imides, sulfonamides, and other compounds can be used as the acid/pronucleophile, this reaction is useful for the preparation of a wide variety of functional groups. This Focus Review of the Mitsunobu reaction summarizes its origins, the current understanding of its mechanism, and recent improvements and applications. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.link_to_subscribed_fulltex

Organocatalytic Mitsunobu reactions

A catalytic Mitsunobu reaction system is described in which the azo reagent is used as an organocatalyst and iodosobenzene diacetate is used as the stoichiometric oxidant. In this system, iodosobenzene diacetate oxidizes the formed hydrazine byproduct to regenerate the azo reagent. Yields obtained in the catalytic reactions using a variety of carboxylic acids and alcohols were slightly lower than those obtained from corresponding stoichiometric reactions. Both primary and secondary alcohols can be used as substrates in this reaction system, with the secondary alcohols affording products with inverted stereochemistry at the carbinol center. Copyright © 2006 American Chemical Society.link_to_subscribed_fulltex

Organocatalytic mitsunobu reactions with 3,5-dinitrobenzoic acid

A second generation procedure for organocatalytic Mitsunobu reactions using 3,5-dinitrobenzoic acid as the pro-nucleophile has been developed. The increased acidity of this acid compared to 4-nitrobenzoic acid, which was used in the original procedure, allowed for higher isolated yields of the desired products and eliminated formation of undesired acetate byproducts. © Georg Thieme Verlag Stuttgart - New York.link_to_subscribed_fulltex

Macroporous polystyrene-supported (diacetoxyiodo)benzene: An efficient heterogeneous oxidizing reagent

A heterogeneous, cross-linked macroporous polystyrene-supported (diacetoxyiodo) benzene reagent has been prepared. This reagent is completely insoluble in all solvents and has a rigid pore structure that allows it to function without the need for swelling. Its utility in a variety of oxidation reactions has been demonstrated. © Georg Thieme Verlag Stuttgart.link_to_subscribed_fulltex

La imagen de la colonia española de las islas Carolinas a través de los hombres que sirvieron en ella.

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A Multipolymer System for Organocatalytic Alcohol Oxidation.

A system involving two polymer-supported reagents for the selective and organocatalytic oxidation of alcohols to aldehydes or ketones has been developed in which both polymeric reagents can be recovered and reused. © The Royal Society of Chemistry 2005.postprin

Time-resolved resonance Raman and density functional theory investigation of the 4-biphenylnitrene dimerization reaction

This paper reports time-resolved resonance Raman spectra for the triplet 4-biphenylnitrene and its reaction to form an azo dimer product (bis-biphenyl-4-yldiazene) in acetonitrile solution. The properties of the triplet 4-biphenylnitrenes were examined based on the results of UBPW91/cc-PVDZ computations. 4-Biphenylnitrene and its azo dimer product were also compared with results previously reported for the 4-methoxyphenylnitrene and its azo dimer product, respectively. The substitution effect of p-phenyl and p-methoxy moieties on the structure and properties of arylnitrenes and azobenzenes are briefly discussed. Copyright © 2004 John Wiley & Sons, Ltd.link_to_subscribed_fulltex

Time-resolved resonance Raman study of the reaction of the 2-fluorenylnitrenium ion with 2-fluorenylazide

A time-resolved resonance Raman investigation of the reaction of the 2-fluorenylnitrenium ion with 2-fluorenylazide in a mixed aqueous solvent is presented. The reaction of the 2-fluorenylnitrenium ion with 2-fluorenylazide in the mixed aqueous solution generates two new species on the microsecond time scale. One of these species is identified as 2,2′-azobisfluorene, and the other species is tentatively assigned to a 1,4-bis-(2,2′-fluorenyl)- tetrazadiene cation intermediate. The structure and properties of these two species are briefly discussed. The reaction of the 2-fluorenylnitrenium ion with 2-fluorenylazide is also briefly compared to that of the 2-fluorenylnitrenium ion reactions with guanosine and water. © 2007 American Chemical Society.link_to_subscribed_fulltex