has been shown to serve as important intermediates for producing α-quaternary alkyl derivatives 8, which were readily transformed into the title compound (−)-1. The reversibility of the thio-Claisen rearrangement, 15⇌8, was clearly demonstrated and appears to be unprecedented. Solvent effects to alter the equilibrium position were studied and found to have only a moderate, but beneficial effect. The
使用
硫代羰基形式 9 的手性双环内
酰胺已被证明是生产 α-季烷基衍
生物 8 的重要
中间体,这些衍
生物很容易转化为标题化合物 (-)-1。
硫代-克莱森重排 15⇌8 的可逆性得到了清晰的证明,而且似乎是前所未有的。研究了改变平衡位置的溶剂效应,发现仅具有中等但有益的效应。通过 10 个步骤从双环内
酰胺 9 中以 14% 的总收率获得标题化合物。