Diastereofacial selection in nitrile oxide cycloaddition reactions. The anti-directing effect of an allylic oxygen and some new results on the ring metalation of isoxazolines. A synthesis of (.+-.)-blastmycinone
作者:Alan P. Kozikowski、Arun K. Ghosh
DOI:10.1021/jo00189a024
日期:1984.7
the adducts to known γ-lactones. The stereochemistry associated with the metalation/alkylation of 5-alkoxymethyl-substituted isoxazolines has also been probed in order to further expand the use of these heterocycles as aldol equivalents in natural products total synthesis. A synthesis of (±)-blastmycinone (34) is reported which combines the two foregoing aspects of stereocontrol. The levels of regio-
已经研究了与腈氧化物与带有烯丙基氧取代基的烯烃的反应有关的非对映选择性的程度。当3-丁烯-2-醇(5)或(+)-(S)-异亚丙基-3-丁烯-1,2-二醇(1)的叔丁基二甲基甲硅烷基醚衍生物为1时,已发现合理的非对映选择性水平。用作双极亲虫。这些环加成反应的立体化学过程已通过将加合物转化为已知的γ-内酯的方法得到严格证明。还探索了与5-烷氧基甲基取代的异恶唑啉的金属化/烷基化有关的立体化学,以进一步扩展这些杂环作为天然产物总合成中的羟醛等效物的用途。据报道,(±)-blastcincinone(34)的合成结合了立体声控制的上述两个方面。还讨论了在由异亚丙基-D-甘油醛制得的顺式和反式二取代的烯烃35和39的环加成反应中发现的区域选择性和立体选择性。给出了手性烯烃与手性腈的反应的单个例子。