Regioselective Synthesis of Nitrones by Decarboxylative Oxidation of<i>N</i>-Alkyl-<i>α</i>-amino Acids and Application to the Synthesis of 1-Azabicyclic Alkaloids
were prepared by catalytic oxidation of the corresponding chiral pyrrolidines in a regioselective manner. These chiral cyclic nitrones, 17 and 45 are versatile intermediates for the synthesis of optically active nitrogen heterocycles, since stereoselective additions of carbon nucleophiles to these chiral nitrones can be readily performed. Typically, ZnI2-mediated addition of ketene t-butyldimethylsilyl
synthesis of nitronesfrom bench stable amines has been developed under constant current electrolysis at room temperature, rendering metal and external oxidant-free protocol in an alkaline medium. The electrocatalysis steps of reported strategy involve anodic oxidation of benzyl amines followed by cathodic reduction of nitro-functional group in an undivided cell affording functional nitrones. The robustness
The tungstate-catalyzed oxidation of N-alkyl-alpha-amino acids with hydrogen peroxide under phase-transfer conditions gives the corresponding nitrones in satisfactory yield.
Transition-metal catalyzed asymmetric 1,3-dipolar cycloaddition reactions between alkenes and nitrones
作者:Kurt V. Gothelf、Karl Anker Joergensen
DOI:10.1021/jo00098a029
日期:1994.9
A transition-metal-catalyze denantioselective 1,3-dipolar cycloaddition reaction between alkenes and nitrones has been developed employing 10 mol % of a chiral titanium catalyst generated in situ from Ti(i-OPr)(2)Cl-2 and chiral diols. Diastereofacial discrimination in favor of the exo isomer was achieved in up to a 95:5 ratio. Isoxazolidines with an optical purity of up to 62% ee are obtained from this reaction. By precipitation of a racemate of one of the isoxazolidines an optical purity of >95% ee is obtained.
STAMM H.; STEUDLE H., TETRAHEDRON, 1979, 35, NO 5, 647-650