Selective uni- and bidirectional homologation of diborylmethane.
Selective uni- and bidirectional homologation of diborylmethane.
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DOI：
10.1039/c6sc05338f
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发表时间：
2017-04-01
期刊：
影响因子：
8.4
通讯作者：
Aggarwal VK
中科院分区：
文献类型：
--
作者：
Blair DJ;Tanini D;Bateman JM;Scott HK;Myers EL;Aggarwal VK
二硼基甲烷可以通过对映体纯锂稳定类碳化合物得到1,2-和1,3-二硼酯进行单向和双向同源化。二硼基甲烷可以通过对映体纯锂稳定类碳化合物分别得到1,2-和1,3-双（硼酯），收率高，对映选择性和非对映选择性高。转化对位阻的高灵敏度使得任何一种歧管都可以单独操作，通过明智地选择类碳化合物的类型来实现，类碳化合物可以是spartin2连接的或无二胺的锂化苯甲酸酯/氨基甲酸酯。这样生成的1,2-二（硼酯）的范围与烯烃的不对称二硼化所包含的范围是互补的，因为一级-二级和一级-三级1,2-二（硼酯）可以以同样高的选择性制备，并且官能团，如末端炔和烯烃，是耐受的。本文还描述了形成c2对称和非对称的反和顺1,3-双（硼酯）的方法，这些方法是通向1,3功能化合成中间体的有力途径。
Diborylmethane can be homologated uni- and bidirectionally by using enantiomerically pure lithium-stabilized carbenoids to give 1,2- and 1,3-bis(boronic esters). Diborylmethane can be homologated uni- and bidirectionally by using enantiomerically pure lithium-stabilized carbenoids to give 1,2- and 1,3-bis(boronic esters), respectively, in good yield and with excellent levels of enantio- and diastereoselectivity. The high sensitivity of the transformation to steric hindrance enables the exclusive operation of either manifold, effected through the judicious choice of the type of carbenoid, which can be a sparteine-ligated or a diamine-free lithiated benzoate/carbamate. The scope of the 1,2-bis(boronic esters) so generated is complementary to that encompassed by the asymmetric diboration of alkenes, in that primary–secondary and primary–tertiary 1,2-bis(boronic esters) can be prepared with equally high levels of selectivity and that functional groups, such as terminal alkynes and alkenes, are tolerated. Methods for forming C 2-symmetric and non-symmetrical anti and syn 1,3-bis(boronic esters) are also described and represent a powerful route towards 1,3-functionalized synthetic intermediates.