Erythro-selective addition of crotyltrialkyltins to aldehydes regardless of the geometry of the crotyl unit. Stereoselection independent of the stereochemistry of precursors
Erythro-selective addition of crotyltrialkyltins to aldehydes regardless of the geometry of the crotyl unit. Stereoselection independent of the stereochemistry of precursors
复制标题
无论巴豆基单元的几何形状如何，巴豆基三烷基锡对醛的红选择性加成。
DOI：
10.1021/ja00543a040
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发表时间：
1980
影响因子：
15
通讯作者：
K. Maruyama
中科院分区：
文献类型：
--
作者：
Yoshinori Yamamoto;H. Yatagai;Y. Naruta;K. Maruyama
从表I中可以明显看出，无论醛的取代基R的空间效应和巴豆基单元的几何形状如何，都实现了赤型选择性（> 90%）缩合。这种与起始材料的立体化学的独立性对于合成应用是特别有用的，并且更重要的是，对于机理考虑是高度令人感兴趣的。方案I显示了导致邻位和苏位衍生物的过渡态，其中Sn与氧（或-OBFj基团）之间的螯合物形成并不重要。[10]很容易确定，在八种可能的几何构型中，由于空间原因，导致邻位异构体的两种构型（D和DO）必须是有利的。因此，本反应体系大概不涉及常规的循环机制; 11先前的反应
As is apparent from Table I, the erythro-selective (> 90%) condensation is realized regardless of the steric effect of the substituent R of aldehydes and of the geometry of the crotyl unit. Such an independence from the stereochemistry of the starting materials is particularly useful for synthetic application and, more importantly, highly interesting for the mechanistic consideration. Scheme I shows thetransition states leadingto erythro and threo derivatives, 9 in which the chelate formation between Sn and oxygen (or-OBFj group) is not important. 10* It is easily decided that, among eight possible geometries, two configurations (D and DO leading to the erythro isomer must be favored for steric reasons. Consequently, the present reaction system presumably does not involve a conventional cyclic mechanism; 11 the previous reaction