Five- and six-membered aromatic rings bearing a methyl group are important molecular fragments in drug discovery. From the medicinal chemistry standpoint, the methyl group might play a pivotal role in improving the biological activities and druggability due to its capability in modulating the molecular conformation as well as the physical and chemical properties (such as lipophilicity and metabolism, etc.). How to effectively install a methyl group in a designated position of an aromatic ring is a long-stand quest and a research hot spot for both medicinal chemists and synthetic organic chemists. In the past few years, significant progresses have been achieved in this field wherein the C–H bond activation and direct methylation become achievable in one step under catalytic conditions. A variety of metal catalysts reported by several research groups are capable of such transformation. The relatively mild reaction conditions and high functional group compatibility make such transformation very attractive for final step synthesis. This paper summarizes such transformation based on their reaction mechanisms, and systematically discusses the reaction conditions and their application of a variety of substrates. It provides both medicinal and synthetic organic chemists the convenience for accessing the most up-to-date methodology, and would foster the potential applications in drug discovery and organic synthesis projects.

带有甲基的五元和六元芳环是药物发现中的重要分子片段。从药物化学的角度来看，由于甲基能够调节分子构象以及物理和化学性质（如亲脂性和代谢等），因此它可能在提高生物活性和成药性方面发挥关键作用。如何在芳香环的指定位置有效地安装甲基，是药物化学家和有机合成化学家长期以来的探索和研究热点。在过去几年中，该领域取得了重大进展，其中在催化条件下可以一步实现 C-H 键活化和直接甲基化。几个研究小组报道的各种金属催化剂都能够进行这种转化。相对温和的反应条件和高官能团兼容性使得这种转化对于最后一步合成非常有吸引力。本文根据它们的反应机理总结了这种转化，并系统地讨论了各种底物的反应条件及其应用。它为药物和合成有机化学家提供了获取最新方法的便利，并将促进药物发现和有机合成项目中的潜在应用。本文根据它们的反应机理总结了这种转化，并系统地讨论了各种底物的反应条件及其应用。它为药物和合成有机化学家提供了获取最新方法的便利，并将促进药物发现和有机合成项目中的潜在应用。本文根据它们的反应机理总结了这种转化，并系统地讨论了各种底物的反应条件及其应用。它为药物和合成有机化学家提供了获取最新方法的便利，并将促进药物发现和有机合成项目中的潜在应用。