Lamba Manisha, Singh Prasoon Raj, Goswami Avijit
Department of Chemistry, SS Bhatnagar Block, Indian Institute of Technology Ropar, Punjab140001, India.
J Org Chem. 2024 Aug 16;89(16):11244-11260. doi: 10.1021/acs.joc.4c00903. Epub 2024 Aug 6.
In this study, we have disclosed N-alkylation and C-alkylation reactions of 2-oxindoles with secondary alcohols. Interestingly, these chemoselective reactions are tunable by changing the reaction conditions. Utilization of protic solvent and Brønsted acid catalyst afforded C-alkylation, whereas, aprotic solvent and Lewis acid catalyst afforded N-alkylation of 2-oxindoles in good to excellent yields. Regioselectivity is achieved by protecting the N-center of the oxindole and C5 alkylated product is furnished exclusively. This protocol is notable because it demonstrates functionalization at the C7 position of oxindole without the need for any directing group at the N-center. Further, a new protocol has been reported for C-H oxygenation at the benzylic position of one of the C5 alkylated derivative.
在本研究中，我们揭示了2-氧化吲哚与仲醇的N-烷基化和C-烷基化反应。有趣的是，这些化学选择性反应可通过改变反应条件来调节。使用质子溶剂和布朗斯特酸催化剂可实现C-烷基化，而使用非质子溶剂和路易斯酸催化剂则能以良好至优异的产率实现2-氧化吲哚的N-烷基化。通过保护氧化吲哚的N中心实现区域选择性，并专一性地得到C5烷基化产物。该方法值得注意，因为它展示了在氧化吲哚的C7位进行官能团化，而无需在N中心使用任何导向基团。此外，还报道了一种用于其中一种C5烷基化衍生物苄基位置的C-H氧化的新方法。
