Transition structures of aldol reactions
Transition structures of aldol reactions
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羟醛反应的过渡结构
DOI：
10.1021/ja00219a067
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发表时间：
1988
影响因子：
15
通讯作者：
K. Houk
中科院分区：
文献类型：
--
作者：
Yi Li;M. Paddon;K. Houk
（Re=烷基，Rz= H）给出抗。如图4所示，醛取代基R ‘ ’在两种情况下都倾向于平伏键。由于Z烯醇化反应比E烯醇化反应具有更高的立体选择性，Dubois和Heathcock都提出，过渡结构偏离了形成CC键的理想60扭角，< f>，向90扭角倾斜。4 . TAS烯醇化物总是产生同步产物，有人认为这些产物是由< j>= 180的无环非螯合过渡结构形成的。在这种情况下，(1)(a)匹兹堡和加州大学洛杉矶分校(b)匹兹堡；永久地址：澳大利亚新南威尔士大学，(c)匹兹堡和加州大学洛杉矶分校，地址与加州大学洛杉矶分校通信
(Re= alkyl, Rz= H) give the anti. 3 As shown in 4, the aldehyde substituent, R", prefers to be equatorial in both cases. Because Z enolates react with higherstereoselectivity than the E enolates, it has been proposedby both Dubois and Heathcock that the transition structures are skewed away from the idealized 60 torsional angle about the forming CC bond,< f>, toward a 90 torsional angle. 4 TAS enolates always give syn products, and it has been suggested that these are formed from the acyclic nonchelated transition structure with< j>= 180. 5 In such cases,(1)(a) Pittsburgh and UCLA (b) Pittsburgh; permanent address: University of New South Wales, Australia,(c) Pittsburgh and UCLA, address correspondence to UCLA