Palladium(0)-Catalyzed Synthesis of Medium-Sized Heterocycles by Using Bromoallenes as an Allyl Dication Equivalent
作者:Hiroaki Ohno、Hisao Hamaguchi、Miyo Ohata、Shohei Kosaka、Tetsuaki Tanaka
DOI:10.1021/ja048693x
日期:2004.7.1
We have developed a highly regio- and stereoselective synthesis of medium-sized heterocycles containing one or two heteroatoms via cyclization of bromoallenes bearing an oxygen, nitrogen, or carbon nucleophilic functionality in the presence of a palladium(0) catalyst and alcohol. In this reaction, bromoallenes act as an allyl dication equivalent, and the intramolecular nucleophilic attack takes place
我们开发了一种高度区域选择性和立体选择性合成的中等大小杂环,通过在钯 (0) 催化剂和醇的存在下,带有氧、氮或碳亲核官能团的溴丙二烯环化。在该反应中,溴丙二烯充当烯丙基双阳离子等价物,分子内亲核攻击仅发生在丙二烯部分的中心碳原子上。有趣的是,具有五原子系链的碳亲核试剂的溴丙二烯可提供具有反式构型的八元环,而具有氧或氮亲核试剂的溴丙二烯则选择性地提供相应的顺式环。这是第一个证明通过溴丙二烯环化合成中等大小环的例子,