作者:Frank Richter、Matthias Bauer、Caroline Perez、Cäcilia Maichle-Mössmer、Martin E. Maier
DOI:10.1021/jo016116a
日期:2002.4.1
were prepared and reacted in the presence of zinc metal with ethyl 2-bromomethylacrylate to provide in a Reformatsky-like reaction alpha-methylene lactones carrying a dienyl side chain. Thermolysis of these compounds (11, 21, 29, and 37) gave in an intramolecular Diels-Alder reaction the corresponding tricyclic cycloadducts (51, 52, 53, and 54). The cycloadditions took place with good diastereoselectivity
制备了几种二烯,并在金属锌的存在下与2-溴甲基丙烯酸乙酯反应,以在Reformatsky样反应中提供带有二烯基侧链的α-亚甲基内酯。这些化合物(11、21、29和37)的热解在分子内Diels-Alder反应中给出了相应的三环环加合物(51、52、53和54)。环加成反应具有良好的非对映选择性和产率。主要异构体的立体化学符合环加合物51、52和54的内过渡态。在一种情况下(化合物58),该结构由X射线晶体学支持。与其他底物相反,壬三烯29环化成exo产物53exo。立体化学情况也可以通过NOESY NMR证明。然而,