International Joint Research Center for Molecular Science, College of Chemistry and Environmental Engineering, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, China.
Division of Chemistry & Mathematical Science, School of Physical & Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore.
Angew Chem Int Ed Engl. 2021 Jun 25;60(27):14817-14823. doi: 10.1002/anie.202102177. Epub 2021 May 24.
Azolium cumulenolates are a special type of intermediates in N-heterocyclic carbene catalysis. They contain elongated linear structures with three contiguous C=C bonds and sterically unhindered α-carbon atoms. These structural features make it difficult to develop enantioselective reactions for these intermediates. Here we disclose the first carbene-catalyzed highly enantioselective addition reactions of azolium cumulenolates. The reaction starts with alkynals as the precursors for azolium cumulenolate intermediates that undergo enantioselective addition to activated ketones. From the same set of substrates, both allene and spirooxindole products can be obtained with high yields and excellent enantioselectivities. The allene moieties in our optically enriched products carry rich reactivities and can be transformed to diverse molecules. The spirooxindole scaffolds in our products are important structural motifs in natural products and medicines.
唑啉 cumulenolates 是 N-杂环卡宾催化中的一种特殊中间体。它们含有拉长的线性结构，具有三个连续的 C=C 键和空间上无阻碍的 α-碳原子。这些结构特征使得难以开发这些中间体的对映选择性反应。在这里，我们首次披露了 Carbene 催化的唑啉 cumulenolate 中间体的高对映选择性加成反应。该反应以炔醛作为唑啉 cumulenolate 中间体的前体，该中间体经历对映选择性地与活化酮加成。从同一组底物中，可以以高产率和优异的对映选择性获得两种产物，即烯丙基和螺氧吲哚产物。我们光学纯产物中的烯丙基部分具有丰富的反应性，可以转化为多种分子。我们产物中的螺氧吲哚支架是天然产物和药物中的重要结构基序。
