Gold‐Catalyzed, Intramolecular, Oxygen‐Transfer Reactions of 2‐Alkynyl‐1,5‐diketones or 2‐Alkynyl‐5‐ketoesters: Scope, Expansion, and Mechanistic Investigations on a New [4+2] Cycloaddition
作者:Le‐Ping Liu、Deepika Malhotra、Zhuang Jin、Robert S. Paton、K. N. Houk、Gerald B. Hammond
DOI:10.1002/chem.201101448
日期:2011.9.12
The gold‐catalyzed intramolecular oxygen‐transfer reactions of 2‐alkynyl‐1,5‐diketones or 2‐alkynyl‐5‐ketoesters—obtained from tetra‐n‐butylammonium fluoride mediated Michael addition of activated allenes to electron‐deficient olefins—furnished cyclopentenyl ketones under very mild conditions. These reactions proceeded much easier and faster than similar reactions reported in literature, and the corresponding
金-催化的2-炔基-1,5-二酮或2-炔基-5-酮酸酯的分子内氧转移反应,得自氟化四正丁基铵介导的迈克尔逊将加成的活化烯加成至电子不足的烯烃,即环戊烯基酮在非常温和的条件下。与文献报道的类似反应相比,这些反应进行得更加容易和快捷,并且以非常高的收率获得了相应的产物。在环异构机理的研究是由两种方式进行18同位素实验和量子化学计算。设计的同位素实验和理论计算的结果均令人满意地支持了新型提议的分子内[4 + 2]环抱法,将含金的intermediate中间体与羰基取代,而不是先前公认的[2 + 2]途径。