A Supramolecular Strategy for Selective Catalytic Hydrogenation Independent of Remote Chain Length
A Supramolecular Strategy for Selective Catalytic Hydrogenation Independent of Remote Chain Length
复制标题
DOI：
10.1021/jacs.9b05604
复制
发表时间：
2019-07-31
影响因子：
15
通讯作者：
Toste, F. Dean
中科院分区：
文献类型：
--
作者：
Bender, Trandon A.;Bergman, Robert G.;Toste, F. Dean
在复杂底物上进行选择性转化仍然是合成化学中的一个挑战。这些困难通常是由于交叉反应性引起的，特别是在多个位点存在类似的官能团时。因此，对这些官能团进行选择性激活的能力是非常重要的。我们在这里报告了一种超分子策略，其中氢化催化剂的封装使烯烃选择性氢化，即使在多个不饱和位点的存在。虽然该反应需要至少一个不要求立体的烯烃取代基，但氢化速率对烯烃与另一个取代基上的官能团（包括羧酸盐）之间的距离不敏感。这一观察结果表明，只有双键被包封才能实现氢化。进一步，我们证明了这种超分子策略可以克服自由催化剂固有的烯丙醇选择性，实现超分子催化剂定向的区域选择性，而不是定向基团选择性。
Performing selective transformations on complex substrates remains a challenge in synthetic chemistry. These difficulties often arise due to cross-reactivity, particularly in the presence of similar functional groups at multiple sites. Therefore, there is a premium on the ability to perform selective activation of these functional groups. We report here a supramolecular strategy where encapsulation of a hydrogenation catalyst enables selective olefin hydrogenation, even in the presence of multiple sites of unsaturation. While the reaction requires at least one sterically nondemanding alkene substituent, the rate of hydrogenation is not sensitive to the distance between the alkene and the functional group, including a carboxylate, on the other substituent. This observation indicates that only the double bond has to be encapsulated to effect hydrogenation. Going further, we demonstrate that this supramolecular strategy can overcome the inherent allylic alcohol selectivity of the free catalyst, achieving supra molecular catalyst-directed regioselectivity as opposed to directing-group selectivity.