Development of Palladium-Catalyzed Decarboxylative Allylation of Electron-Deficient Sulfones and Identification of Unusual Side Products
作者:Monica A. Gill、Jeffrey M. Manthorpe
DOI:10.1021/acs.joc.9b00068
日期:2019.5.17
The use of sulfones as electron-withdrawing groups in substrates for palladium-catalyzed decarboxylative allylation was explored. A previously published trifluoromethanesulfonyl-based substrate was highly reactive and selective under mild conditions, but the substrate scope was not readily expanded. Instead, 3,5-bis(trifluoromethyl)phenyl sulfones were employed, thereby simultaneously retaining most
探索了使用砜作为底物在钯催化的脱羧烯丙基化中的吸电子基团。先前公开的基于三氟甲磺酰基的底物在温和条件下具有高反应性和选择性,但底物范围不易扩展。取而代之的是,使用了3,5-双(三氟甲基)苯基砜,从而同时保留了大多数电子缺陷并提供了方便的合成途径。优化催化条件以最大程度地将产物分布提高到质子化副产物上可合成的烯丙基化产物的合成水平,极具挑战性,Pd 2(dba)3产生的结果不一致且不可再现作为钯的来源。各种底物在四氢呋喃中于50°C的条件下经受了PdCp(1-肉桂基)和Xantphos的优化催化条件,持续30分钟。这些条件适用于所有底物,但α,α-二甲基烯丙基酯除外,它需要更多的施力条件并提供四种产物:预期的烯丙基化和质子化产物,以及环丙基化产物和空前的假二聚产物。考虑了形成这些异常副产物的机理。