Deproto-metallation using a mixed lithium–zinc base and computed CH acidity of 1-aryl 1H-benzotriazoles and 1-aryl 1H-indazoles
作者:Elisabeth Nagaradja、Floris Chevallier、Thierry Roisnel、Vincent Dorcet、Yury S. Halauko、Oleg A. Ivashkevich、Vadim E. Matulis、Florence Mongin
DOI:10.1039/c3ob42380h
日期:——
1-Aryl-1H-benzotriazoles and -1H-indazoles were synthesized, and their deproto-metallation using the base prepared by mixing LiTMP with ZnCl2·TMEDA (1/3 equiv.) was studied. In the indazole series, reactions occurring at the 3 position were followed by ring opening, and functionalization of the substrate was only found possible (on the sulfur ring) using 2-thienyl as aryl group. In the benzotriazole series, either mono- or bis-deprotonation (depending on the amount of base employed) was achieved with phenyl, 4-methoxyphenyl and 2-thienyl as aryl group, and bis-deprotonation in the case of 4-chlorophenyl and 4-trifluoromethylphenyl. The experimental results were analyzed with the help of the CH acidities of the substrates, determined in THF solution using the DFT B3LYP method.