Selectivity in reactions of allyl diazoacetates as a function of catalyst and ring size from γ-lactones to macrocyclic lactones
Selectivity in reactions of allyl diazoacetates as a function of catalyst and ring size from γ-lactones to macrocyclic lactones
复制标题
从γ-内酯到大环内酯的重氮乙酸烯丙酯反应中的选择性是催化剂和环尺寸的函数
DOI：
10.1021/jo005589z
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发表时间：
2000-12-29
影响因子：
3.6
通讯作者：
Hu, WH
中科院分区：
文献类型：
--
作者：
Doyle, MP;Hu, WH
研究了通过0、1、2和3个乙二醇单元连接到烯丙基上的重氮乙酸酯的催化反应的化学选择性、非对映选择性和对映选择性。从环丙烷化，碳氢插入，和oxonium叶立德生成的结果进行比较，从铜（I）和dirhodium（II）的羧酸盐和carboxamidates的非手性和手性催化剂的反应。相对于重氮乙酸乙酯与烯丙基乙基醚的分子间反应的结果，分子间反应显示出多样性的选择性，包括与重氮乙酸乙酯相反的构型排列;一种优选用于相应的分子间环丙烷化反应，环丙烷化的对映体选择性以反映碳-环丙烷化的发散轨迹的方式取决于催化剂配体。碳双键的反应卡宾中心。对映体选择性随着手性铜催化剂的环尺寸而增加，但手性二铑（II）羧酰胺化物发生相反的情况。机制的影响，包括与反应金属卡宾的构象相关的影响，提供了：理解催化不对称环丙烷化反应中对映选择性的新维度。
Catalytic reactions of diazoacetates tethered through zero, one, two, and three ethylene glycol units to an allyl group have been investigated for chemoselectivity, diastereoselectivity and enantioselectivity. Results from cyclopropanation, carbon-hydrogen insertion, and oxonium ylide generation are,compared from reactions of achiral and chiral catalysts of copper(I)and dirhodium(II) carboxylates and carboxamidates. Relative to results from intermolecular reactions of ethyl diazoacetate with allyl ethyl ether, intermolecular reactions show a diversity of selectivities including preference for the opposite configurational arrangement from the; one preferred in corresponding intermolecular cyclopropanation reactions, Enantioselectivities for cyclopropanation are dependent on the catalyst ligands in a manner that reflects divergent trajectories of the carbon-carbon double bond to the reacting carbene center. Enantioselectivity increases as a function of ring size with chiral,copper catalysts, but the reverse occurs with chiral dirhodium(II) carboxamidates. Mechanistic implications, including those related to the conformation of the reacting metal carbene, offer:a new dimension to understanding of enantioselectivity in catalytic asymmetric cyclopropanation reactions.