Pd-catalyzed arylation or benzylation of nitroazoles using aryl sulfonates or benzyl acetates is described. Electronically varied aryl tosylates and mesylates, as well as benzyl acetates, afford the arylated and benzylated products. Arylation of nitrobenzene is also reported. The relative rate for the arylation of halides is greater than that of tosylates using the reported reaction parameters. These studies enhance the scope of electrophiles for nitroarene arylations and benzylations, which was hitherto limited to the use of halide electrophiles.
Catalytic C–H Allylation and Benzylation of Pyrazoles
作者:Seri Bae、Ha-Lim Jang、Haeun Jung、Jung Min Joo
DOI:10.1021/jo5025317
日期:2015.1.2
general approach for the synthesis of allylated and benzylated pyrazoles. An electron-withdrawing substituent, such as nitro, chloro, and ester groups, at C4 renders the Lewis basic nitrogen atom to be less basic and the C–H bond more acidic than the ones of the parent ring, enabling Pd-catalyzed C–H allylation and benzylation reactions of pyrazoles. The new method expanding the scope of the C–H functionalization