Enantiocontrolled macrocycle formation by catalytic intramolecular cyclopropanation
Enantiocontrolled macrocycle formation by catalytic intramolecular cyclopropanation
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DOI：
10.1021/ja9945414
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发表时间：
2000-06-21
影响因子：
15
通讯作者：
Stanley, SA
中科院分区：
文献类型：
--
作者：
Doyle, MP;Hu, WH;Stanley, SA
用手性铜（I）和铑（II）催化剂研究了分子内环丙烷化反应的立体选择性，结果表明，环丙烷与十元环和更大的环发生了融合。通过在烯丙基双键和重氮乙酸酯之间引入1，2-二甲醇连接基团，考察了烯烃结构和催化剂对反应的影响。控制功能的加成反应，特别是那些非对映体选择性和对映体选择性，已被阐明，它们与金属本身或其伴随的配体，影响的轨迹烯烃的卡宾中心。从五元环到二十元环的环尺寸对立体选择性的影响已经用选定的铜（I）和铑（II）催化剂测定，并且立体控制的变化作为环尺寸的函数可以理解为是由于烯烃轨迹到卡宾中心的变化。氢化物提取从苄基位置伴随着另外当dirhodium催化剂被采用，和分子内C-H插入到烯丙基网站，形成一个九元环已被观察到作为一个主要的竞争反应，但可以忽略不计的enantiocontraction。使用1，8-萘二甲醇。作为连接基导致比使用1，2-苯二甲醇更低的对映选择性。
Stereoselectivity in intramolecular cyclopropanation reactions resulting in cyclopropane fusion with ten- and larger-membered rings has been examined using chiral copper(I) and dirhodium(II) catalysts. The influence of alkene structure and catalyst has been obtained using the 1,2-bonzenedimethanol linker between the allylic double bond and diazoacetate. Control features in the addition reaction, especially those for diastereoselectivity and enantioselectivity, have been elucidated, and they are associated with the metal itself or its attendant ligands that influence the trajectory of the alkene to the carbene center. The influence of ring size, from five- to twenty-membered rings, on stereoselectivity has been determined with selected copper(I) and dirhodium(II) catalysts, and the changes in stereocontrol as a function of ring size can be understood as being due to a change in the olefin trajectory to the carbene center. Hydride abstraction from a benzylic position accompanies addition when dirhodium catalysts are employed, and intramolecular C-H insertion into an allylic site to form a nine-membered ring has been observed as a major competing reaction but with negligible enantiocontrol. The use of 1,8-naphthalenedimethanol. as a linker results in lower enantioselectivity than does use of 1,2-benzenedimethanol.