Cycloaddition Chemistry of 1,3-Thiazolium-4-olate Systems. Reaction with Nitroalkenes and Interpretation of Results Using PM3 Calculations
作者:Martín Avalos、Reyes Babiano、Andrés Cabanillas、Pedro Cintas、Francisco J. Higes、José L. Jiménez、Juan C. Palacios
DOI:10.1021/jo952275g
日期:1996.1.1
room temperature in methylene chloride (48 h) resulted in two readily separable diastereomeric racemic 4,5-dihydrothiophenes via transient cycloadducts that underwent rearrangement under these reaction conditions. Using chiral carbohydrate-derived nitroalkenes, two diastereomeric dihydrothiophenes were obtained, showing that regiospecificity and facial selectivity were involved in these cycloadditions
1,3-噻唑-4-油酸酯的1,3-偶极环加成反应很容易由硫脲基衍生物制备,在室温下于二氯甲烷中(48h)反式-β-硝基苯乙烯生成两个易于分离的非对映异构外消旋体4,5-通过在这些反应条件下进行重排的瞬态环加合物生成二氢噻吩。使用手性碳水化合物衍生的硝基烯烃,获得了两个非对映异构体二氢噻吩,表明这些环加成反应涉及区域特异性和面部选择性。(1)H NMR数据和分离的初始环加合物的捕集实验表明,环加成是可逆的,并说明了观察到的加合物和最终产物的比率。单晶X射线测定确定了关键中间体和产物的结构,