Friedel-Crafts Benzylation of Activated and Deactivated Arenes
作者:Gabriel Schäfer、Jeffrey W. Bode
DOI:10.1002/anie.201105380
日期:2011.11.11
going back makes possible facile Friedel–Craftsbenzylations with moderate reaction temperatures, simple reaction workups, and improved substrate scope for the formation of synthetically important diarylmethanes (see scheme). Upon complexation with BF3⋅OEt2, hydroxamates serve as reversible leaving groups that stabilize highly reactive carbocations. Even deactivatedarenes and electron‐deficient benzylhydroxamates
cross-coupling of thiol derivatives with aryl bromides has now been established. This procedure provides access to simple and complex unsymmetrical diarylmethane molecules under mild reaction conditions with a broad functional group tolerance. The key steps of the reaction involve a silane-mediated halogen-atom transfer (XAT) and a subsequent intramolecular homolytic substitution (SH), forming C-centered
金属光氧化还原过程已成为 C−C 键形成的有效方法。现在已经建立了硫醇衍生物与芳基溴的 Ni-光氧化还原催化脱硫交叉偶联。该过程提供了在具有广泛的官能团耐受性的温和反应条件下获得简单和复杂的不对称二芳基甲烷分子的途径。反应的关键步骤涉及硅烷介导的卤素原子转移 (XAT) 和随后的分子内均裂取代 ( SH ),如机理研究所示,从各种硫醇衍生物形成以C为中心的自由基。这项研究为大量天然存在的硫醇的新转化铺平了道路。