A General Method for Copper-Catalyzed Arylation of Arene C−H Bonds

Abstract

A general method for copper-catalyzed arylation of sp 2 C-H bonds with pKa's below 35 has been developed. The method employs aryl halide as the coupling partner, lithium alkoxide or K 3 PO 4 base, and DMF, DMPU, or mixed DMF/xylenes solvent. A variety of electron-rich and electron-poor heterocycles such as azoles, caffeine, thiophenes, benzofuran, pyridine oxides, pyridazine, and pyrimidine can be arylated. Furthermore, electron-poor arenes possessing at least two electronwithdrawing groups on benzene ring can also be arylated. Two arylcopper-phenanthroline complex intermediates were independently synthesized.

Recent Progress in C—C Cross-Coupling Reaction of PyridineN-Oxides

“…Hartwig 等 [45] CuI 催化的吡啶-N-氧化物的直接芳基化反应历程 主要由 3 个部分组成 [47] ; 首先, 是吡啶-N-氧化物的金属 化, 当 C-H 的酸性较强的时候会增加反应的效率, 甚 至用 K 3 PO 4 就可以金属化. 其次, 金属化的底物和 CuI 在配体菲啰啉存在下发生金属的交换反应, 最后再和芳 基碘发生偶联反应.…”

Current Developments in the Syntheses of 1,2,4-Triazole Compounds

“…The used base for this reaction was depended on the acidity of the C-H bond. For relatively acidic C-H bonds with pKa below 27, potassium phosphate was employed; when pKa is between 27-35, strong lithium alkoxide base was required [290]. This copper catalyzed arylation is a complementary methodology to existing coupling methods for the preparation of aryl triazole derivatives and offers advantages with regards to the number of synthetic steps and functional group tolerance.…”

Pd-catalyzed Highly Regio- and Stereocontrolled Direct Alkenylation of Electron-deficient Polyfluoroarenes

“…The advantages of this reaction are its high regioand stereoselectivity, mild reaction temperature (70°C), and the use of readily available Pd(PPh 3 ) 4 . This approach provides a useful access to polyfluoroarylated derivatives of interest in both life and materials science.…”

“…2 Since the first example of palladiumcatalyzed direct arylation of polyfluoroarenes with arylhalides was reported by Fagnou, 3 impressive progress in direct functionalization of polyfluoroarenes has been made. 4 However, many of these efforts mainly focused on the direct arylation of polyfluoroarenes.…”