Highly Diastereoselective Nitrone Cycloaddition onto a Chiral Ketene Equivalent: Asymmetric Synthesis of Cispentacin
作者:Varinder K. Aggarwal、Stephen J. Roseblade、Juliet K. Barrell、Rikki Alexander
DOI:10.1021/ol025665f
日期:2002.4.1
[reaction: see text] A highly diastereoselective intramolecular nitrone cycloaddition onto a chiral ketene equivalent, obtained by Horner-Wadsworth-Emmons olefination of either enantiomer of bis-sulfinyl phosphonate6, is described. Cycloaddition gave 5,5-disubstituted isoxazolidine 10 in good yield as a single diastereomer. Catalytic hydrogenolysis of 10 furnished either enantiomer of optically pure
The use of enantiomerically pure ketene dithioacetal bis(sulfoxides) in highly diastereoselective intramolecular nitrone cycloadditions. Application in the total synthesis of the β-amino acid (–)-cispentacin and the first asymmetric synthesis of cis-(3R,4R)-4-amino-pyrrolidine-3-carboxylic acid
作者:Varinder K. Aggarwal、Stephen Roseblade、Rikki Alexander
DOI:10.1039/b212719a
日期:2003.2.11
corresponding 5,5-disubstituted isoxazolidine as a single diastereomer in good yield. This reaction has been used as the key step in an asymmetricsynthesis of the naturally occurring antibiotic, (-)-cispentacin. An asymmetricsynthesis of 4-amino-pyrrolidine-3-carboxylic acid has also been carried out using the intramolecular nitrone cycloaddition as the stereocontrolling step.