The nitrile oxide/isoxazoline approach to eleven-carbon monosaccharides: cycloaddition of d- and l-arabinonitrile oxides to 5,6-dideoxyhex-5-enofuranoses and characterisation of the resulting 2-isoxazolines
作者:Robert O. Gould、Karen E. McGhie、R.Michael Paton
DOI:10.1016/s0008-6215(98)00323-1
日期:1999.11
reaction of nitrile oxide 5 with d -Man-derived alkene 8 proceeded similarly yielding 4,5-dihydroisoxazoles 17 and 18 (82:18). Comparable levels of π-facial selectivity (66–76% d.e.) in favour of 5R-adducts were observed for the reactions of l -Ara-derived nitrile oxide 6 with alkenes 7 and 8 to form dihydroisoxazoles 23 / 24 and 25 / 26 , thus demonstrating that the configuration of the nitrile oxide component
摘要碱诱导的羟肟基氯10的脱氯化氢反应生成的2,3:4,5-二-O-异亚丙基-d-阿拉伯腈氧化物5环加成到d-Glc衍生的烯烃7上,得到89:11的非对映异构体混合物(5 R)-和(5 S)-3-(1,2:3,4-二-O-异亚丙基-d-阿拉伯糖-四糖醇-1-基)-5-(3-O-苄基-1, 2-O-异亚丙基-α-d-xylo-四呋喃基-4-基)-4,5-二氢异恶唑11和12。氧化腈5与d-Man衍生的烯烃8的相应反应类似地进行,得到4,5-二氢异恶唑17和18(82:18)。在l -Ara衍生的丁腈氧化物6与烯烃7和8形成二氢异恶唑23/24和25/26的反应中,观察到可比较的π面选择性(66-76%de)有利于5R加合物的水平,因此证明环加成中的腈氧化物组分的构型对反应的立体化学结果影响很小。通过X射线晶体学测定二氢异恶唑啉23的结构,并与由相同烯烃制备的已知类似物进行比较,从其物理和光谱