Department of Chemistry , University of California , Irvine , California 92697 , United States.
College of Pharmacy , Liaocheng University , Liaocheng , Shandong 252059 , China.
J Am Chem Soc. 2019 Feb 20;141(7):3006-3013. doi: 10.1021/jacs.8b11395. Epub 2019 Feb 8.
In this Article, we expand upon the catalytic hydrothiolation of 1,3-dienes to afford either allylic or homoallylic sulfides with high regiocontrol. Mechanistic studies support a pathway in which regioselectivity is dictated by the choice of counterion associated with the Rh center. Non-coordinating counterions, such as SbF, allow for η-diene coordination to Rh complexes and result in allylic sulfides. In contrast, coordinating counterions, such as Cl, favor neutral Rh complexes in which the diene binds η to afford homoallylic sulfides. We propose mechanisms that rationalize a fractional dependence on thiol for the 1,2-Markovnikov hydrothiolation while accounting for an inverse dependence on thiol in the 3,4- anti-Markovnikov pathway. Through the hydrothiolation of an essential oil (β-farnesene), we achieve the first enantioselective synthesis of (-)-agelasidine A.
在本文中，我们扩展了 1,3-二烯的催化氢硫加成反应，以高区域选择性得到烯丙基或同烯丙基硫醚。机理研究支持这样一种途径，即区域选择性由与 Rh 中心相关的抗衡离子的选择决定。非配位抗衡离子（如 SbF）允许 η-二烯与 Rh 配合物配位，并导致生成烯丙基硫醚。相比之下，配位抗衡离子（如 Cl）有利于中性 Rh 配合物，其中二烯结合 η 以提供同烯丙基硫醚。我们提出的机理合理地解释了在 1,2-Markovnikov 氢硫加成反应中对硫醇的分数依赖性，同时解释了在 3,4-anti-Markovnikov 途径中对硫醇的反比依赖性。通过对一种精油（β-法呢烯）的氢硫加成反应，我们实现了 (-)-阿加雷斯定 A 的首次对映选择性合成。
