Department of Organic Chemistry and Centro de Innovación en Química Avanzada (ORFEO-CINQA). Faculty of Sciences, University of Alicante, E-03080 Alicante, Spain.
Org Biomol Chem. 2019 Jan 16;17(3):482-489. doi: 10.1039/c8ob01811a.
The fluorination of 3-acetyl-2-oxindoles with N-fluorobenzenesulfonimide under Lewis acid catalysis using Mg(ClO4)2 gives the starting compounds 3-acetyl-3-fluoro-2-oxindoles. These compounds are subjected to base-promoted deacylative alkylation (DaA) for the in situ generation of 3-fluoro-2-oxindole enolates under very mild reaction conditions using Triton B (1 equiv.) and alkyl halides and Michael acceptors as electrophilic reagents. The corresponding 3-alkylated-3-fluoro-2-oxindoles are obtained in good to very high yields. In addition, the palladium-catalyzed deacylative allylation is carried out with allylic alcohols using LiOtBu as the base and 6 mol% of Pd(OAc)2 and dppp, giving the resulting 3-allylated 3-fluoro-2-oxindoles in good yields. This methodology allows a simple synthesis of 3-alkylated-3-fluoro-2-oxindoles, which are difficult to obtain by other routes.
在路易斯酸催化下，用 N-氟代苯磺酰亚胺氟化 3-乙酰基-2-氧代吲哚，得到起始化合物 3-乙酰基-3-氟-2-氧代吲哚。这些化合物在非常温和的反应条件下，使用 Triton B（1 当量）和烷基卤化物及迈克尔受体作为亲电试剂，通过碱促进的脱酰基烷基化（DaA）反应，原位生成 3-氟-2-氧代吲哚烯醇化物。相应的 3-烷基化-3-氟-2-氧代吲哚以良好到很高的收率得到。此外，用烯丙醇进行钯催化脱酰基烯丙基化反应，以 LiOtBu 作为碱，Pd(OAc)2 和 dppp 的用量为 6 mol%，得到相应的 3-烯丙基化 3-氟-2-氧代吲哚，产率良好。该方法可用于简单合成 3-烷基化-3-氟-2-氧代吲哚，这些化合物很难通过其他途径获得。
