Pauson-Khand Reaction of Allenic Hydrocarbons: Synthesis of 4-Alkylidenecyclopentenones
作者:Frédéric Antras、Stéphane Laurent、Mohammed Ahmar、Henry Chermette、Bernard Cazes
DOI:10.1002/ejoc.200901224
日期:2010.6
The carbonyldicobalt-mediated alkyne/allene/CO cocyclization gives 4-alkylidenecyclopentenones as the major [2+2+1] cycloadducts. The regio- and stereoselectivities depend mainly on the substitution pattern of both the alkyne and the allenic moieties, which can be rationalized using the Magnus mechanism. However, contrary to this model, and in agreement with more recent mechanistic studies, our results
羰基二钴介导的炔烃/丙二烯/CO 共环化得到 4-亚烷基环戊烯酮作为主要的 [2+2+1] 环加合物。区域选择性和立体选择性主要取决于炔烃和丙二烯部分的取代模式,这可以使用马格努斯机制进行合理化。然而,与该模型相反,并且与最近的机理研究一致,我们的结果提供的证据表明,在初级炔-二钴络合物的一个钴原子上,丙二烯烃的初始伪赤道和伪轴配位模式都是涉及。给出了支持这两种协调模式的 DFT 计算。