The Direct Catalytic Asymmetricα-Aminooxylation Reaction: Development of Stereoselective Routes to 1,2-Diols and 1,2-Amino Alcohols and Density Functional Calculations
for the asymmetric alpha-oxidation reaction and found that several proline derivatives were also able to catalyze the transformation with excellent enantioselectivities. Moreover, stereoselective routes for the synthesis of monoprotected vicinal diols and hydroxyketones were found. In addition, short routes for the direct preparation of enantiomerically pure epoxides and 1,2-amino alcohols are presented
Direct Catalytic Enantioselectiveα-Aminoxylation of Ketones: A Stereoselective Synthesis ofα-Hydroxy andα,α′-Dihydroxy Ketones
作者:Anders Bøgevig、Henrik Sundén、Armando Córdova
DOI:10.1002/anie.200353018
日期:2004.2.20
Direct Amino Acid-Catalyzed Asymmetric Desymmetrization of <i>meso</i>-Compounds: Tandem Aminoxylation/O−N Bond Heterolysis Reactions
作者:Dhevalapally B. Ramachary、Carlos F. Barbas
DOI:10.1021/ol050246e
日期:2005.4.14
A practical organocatalytic process for the synthesis of optically active, highly substituted (x-hydroxy-ketones was achieved through asymmetric desymmetrization (ADS) of prochiral ketones. The ADS and O-N bond reduction reaction of prochiral ketone with nitrosobenzene in the presence of a catalytic amount of chiral amine or amino acid produced the tandem ADS/O-N bond reduced products as single diastereomers with good yields and excellent enantiomeric excesses.
Novel organic catalysts for the direct enantioselective α-oxidation of carbonyl compounds
The proline-derived N-sulfonylcarboxamide-catalyzed direct enantioselective alpha-oxidation of ketones and aldehydes with nitrosobenzene is presented. The reactions proceed smoothly furnishing the corresponding alpha-aminoxylated compounds in good yields with up to > 99% ee. The proline-derived N-sulfonylcarboxamides were also found to be excellent catalysts for the direct enantioselective nitroso Diels-Alder-type reaction between nitrosobenzene and of alpha,beta-unsaturated cyclic ketones yielding the corresponding bicyclic Diels-Alder adduct products with tip to > 99% ee. The proline-derived N-sulfonylcarboxamides represent a readily available and highly modular novel type of organic catalyst. (c) 2005 Elsevier Ltd. All rights reservesd.
Direct Proline-Catalyzed Asymmetric α-Aminoxylation of Aldehydes and Ketones
The direct proline-catalyzedasymmetric α-aminoxylation of aldehydes and ketones has been developed using nitrosobenzene as an oxygen source, affording α-anilinoxy-aldehydes and -ketones with excellent enantioselectivity. Reaction conditions have been optimized, and low temperature (−20 °C) was found to be a key for the successful α-aminoxylation of aldehydes, while slow addition of nitrosobenzene