NHC-catalyzed generation of difluorocarbene and its application to difluoromethylation of oxygen nucleophiles
作者:Kohei Fuchibe、Yuta Koseki、Tatsuya Aono、Hisashi Sasagawa、Junji Ichikawa
DOI:10.1016/j.jfluchem.2011.09.012
日期:2012.1
trimethylsilyl 2,2-difluoro-2-fluorosulfonylacetate (TFDA). Cyclohexenones and tetralones were treated with TFDA in the presence of catalytic amounts of N,N′-dimesitylimidazolium chloride and sodium carbonate. The ketones were difluoromethylated with the generated difluorocarbene to afford enol difluoromethyl ethers without difluorocyclopropanation. The ethers thus obtained were dehydrogenated with DDQ to
由NHC催化剂在温和的条件下,从2,2-二氟-2-氟磺酰基乙酸三甲基甲硅烷基酯(TFDA)开始,控制二氟卡宾的生成。在催化量的氯化N,N′-二甲酰亚胺咪唑鎓和碳酸钠存在下,用TFDA处理环己酮和四氢萘酮。用生成的二氟卡宾将酮二氟甲基化,得到烯醇二氟甲基醚,而没有二氟环丙烷化。将如此获得的醚用DDQ脱氢,以高收率提供芳基二氟甲基醚。在相似的条件下,仲酰胺选择性地在氧原子上进行二氟甲基化反应,得到二氟甲基酰亚胺,从而形成2-二氟甲氧基吡啶。