Synthesis of Ethyl (2RS,3SR)-1-Tosyl-3-Vinylazetidine-2-carboxylate and ethyl (2RS,E)-3-ethylidene-1-tosylazetidine-2-carboxylate (=rac-ethylN-tosylpolyximate)
作者:Hans Bauman、Rudolf O. Duthaler
DOI:10.1002/hlca.19880710513
日期:1988.8.10
The synthesis of 3-ethylideneazetidine-2-carboxylic acid (=polyoximic acid; 3) is a approached in two different ways leading to potential precursors of 3. The first way involved a ring closure to a vinyl-subsatituted azetidin. Thus, Ireland-Claisen rearrangement of the Boc-glycinates 6 and 10 of (Z)- and (E)-2-butene-1,4-diol afforded, after exchange of the N-protecting groups, the isomeric 2-(tos
3-亚乙基氮杂环丁烷-2-羧酸(=聚肟酸;3)的合成是以两种不同的方式进行的,从而导致了潜在的3的前体。第一种方法涉及到乙烯基取代的氮杂环丁烷的闭环。因此,在交换N-保护基团之后,爱尔兰- (Z)-和(E)-2-丁烯-1,4-二醇的Boc-甘氨酸酸酯6和10的克莱森重排提供了异构体2-(甲苯磺酰基氨基)具有高立体选择性的-3-乙烯基丁醇化物13和14。只有顺式异构体14可进一步转化为3-(溴甲基)-2-(甲苯磺酰基)-4-戊烯酸17,并与K A smoth环化2 CO 3,以反式-3- vinylazetidtene -2- carboxylaze 18(方案2)。在第二种方法中,通过[2 + 2]环加成反应以及两种异构体23和24更直接地从茂金属20和(甲苯磺酸)乙酸21中获得了18的3-亚乙基异构体19(方案3)。但是,该反应的主要产物是2-(甲苯磺酰基氨基)-4-己酸22,是烯反应的产物。