Synthesis of 2-deoxy-α-DAH based on diazo chemistry by insertion reactions of 2-diazo-3-deoxy- d - arabino -heptulosonate derivatives mediated by rhodium(II)
作者:F Sarabia、S Chammaa、F.J López Herrera
DOI:10.1016/s0040-4020(01)01074-2
日期:2001.12
corresponding 2-diazo-3-deoxy-heptulosonate derivative 10, which was subjected to the action of rhodium(II). However, the major compound obtained in this reaction was the C-glycofuranoside 12 by the interaction of the benzyl protecting group employed at the OH of C-4 with the carbenoid generated at C-2. To avoid this undesired insertion reaction, aldehyde 13 was selected as a suitable starting material and, following
基于重氮化学的使用描述了2-脱氧-α-DAH(2)的合成,如我们先前在相应的2-脱氧-KDO的合成中所报道的。最初,使用二乙基锌作为促进剂,使d-阿拉伯糖醛-醛糖衍生物3与重氮乙酸乙酯反应。以非常高的收率获得的相应的β-羟基-α-重氮酯4被转化为相应的2-重氮-3-脱氧-庚二酮酸酯衍生物10,其经受铑(II)的作用。然而,在该反应中获得的主要化合物是C-糖呋喃糖苷12通过在C-4的OH处使用的苄基保护基与在C-2产生的类胡萝卜素的相互作用来实现的。为了避免这种不希望的插入反应,选择醛13作为合适的起始原料,并按照与3相同的化学方法,有效地合成了重氮19。最后,由铑(II)所介导的分子内OH插入19提供有针对性的2-脱氧- DAH衍生物21在一个合理的良好的产率,这是最后转化为2-脱氧α-DAH的钾盐2。