Yan Jia-Lei, Maiti Rakesh, Ren Shi-Chao, Tian Weiyi, Li Tingting, Xu Jun, Mondal Bivas, Jin Zhichao, Chi Yonggui Robin
Division of Chemistry & Biological Chemistry, School of Physical & Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore.
Guizhou University of Traditional Chinese Medicine, Guiyang, 550025, China.
Nat Commun. 2022 Jan 10;13(1):84. doi: 10.1038/s41467-021-27771-x.
Axially chiral styrenes bearing a chiral axis between a sterically non-congested acyclic alkene and an aryl ring are difficult to prepare due to low rotational barrier of the axis. Disclosed here is an N-heterocyclic carbene (NHC) catalytic asymmetric solution to this problem. Our reaction involves ynals, sulfinic acids, and phenols as the substrates with an NHC as the catalyst. Key steps involve selective 1,4-addition of sulfinic anion to acetylenic acylazolium intermediate and sequential E-selective protonation to set up the chiral axis. Our reaction affords axially chiral styrenes bearing a chiral axis as the product with up to > 99:1 e.r., > 20:1 E/Z selectivity, and excellent yields. The sulfone and carboxylic ester moieties in our styrene products are common moieties in bioactive molecules and asymmetric catalysis.
在空间位阻较小的非环烯烃和芳基环之间带有手性轴的轴手性苯乙烯，由于轴的旋转势垒较低而难以制备。本文公开了一种用于解决该问题的N-杂环卡宾（NHC）催化不对称方法。我们的反应以炔醛、亚磺酸和酚为底物，以NHC为催化剂。关键步骤包括亚磺酸根阴离子对炔丙酰唑鎓中间体的选择性1,4-加成以及随后的E-选择性质子化以建立手性轴。我们的反应得到了带有手性轴的轴手性苯乙烯产物，其对映体比例高达>99:1，E/Z选择性>20:1，且产率优异。我们苯乙烯产物中的砜和羧酸酯部分是生物活性分子和不对称催化中的常见部分。
