Chelation or Non‐Chelation Control in Addition Reactions of Chiral α‐ and β‐ Alkoxy Carbonyl Compounds [New Synthetic Methods (44)]
Chelation or Non‐Chelation Control in Addition Reactions of Chiral α‐ and β‐ Alkoxy Carbonyl Compounds [New Synthetic Methods (44)]
复制标题
手性α-和β-烷氧基羰基化合物加成反应中的螯合或非螯合控制[新合成方法(44)]
DOI：
--
复制
发表时间：
1984
期刊：
影响因子：
--
通讯作者：
M. Reetz
中科院分区：
文献类型：
--
作者：
M. Reetz
在手性α-或β-烷氧基醛或酮上加入亲核试剂（如格氏试剂或烯醇化物）会产生新的手性中心，因此是非对映性的。为了控制立体选择性，开发了两种策略：(1)使用形成中间螯合物的路易斯酸试剂，从较少阻碍的一侧立体选择性地攻击这些（螯合控制）；(2)使用不能螯合的试剂，立体选择攻击由电子和/或空间因素控制（非螯合控制）。通常，这两种方法导致相反的非对映选择性。通过仔细选择含有Li、Mg、B、Si、Sn、Cu、Zn或Ti等元素的有机金属试剂，可以预测结果。
The addition of C-nucleophiles such as Grignard reagents or enolates to chiral α- or β-alkoxy aldehydes or ketones creates a new center of chirality and is therefore diastereogenic. In order to control stereoselectivity, two strategies have been developed: (1) Use of Lewisacidic reagents which form intermediate chelates, these being attacked stereoselectively from the less hindered side (chelation control); (2) use of reagents incapable of chelation, stereoselective attack being governed by electronic and/or steric factors (non-chelation control). Generally, the two methods lead to the opposite sense of diastereoselectivity. It is possible to predict the outcome by careful choice of organometallic reagents containing elements such as Li, Mg, B, Si, Sn, Cu, Zn, or Ti.
For corrigendum see DOI:10.1002/anie.198407461