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 phosphonate 6, 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
[反应:见正文]描述了通过手性双亚磺酰基膦酸酯6的对映体的霍纳-沃兹沃思-埃蒙斯烯化获得的高度非对映选择性的分子内氮酮环加成到手性烯酮上。环加成以单个非对映体的高收率得到5,5-二取代的异恶唑烷10。催化氢解10种旋光纯的顺式-2-氨基环戊烷-1-羧酸的对映异构体。