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.
合成了1-芳基-1H-苯并三唑和-1H-吲唑,并研究了它们在使用LiTMP与ZnCl2·TMEDA(1/3当量)混合制备的碱时的去质子化金属化反应。在吲唑系列中,发生在3位的反应伴随环的打开,且基底的功能化仅在使用2-噻吩基作为芳基时(在硫环上)发现是可能的。在苯并三唑系列中,根据所用碱的量,分别实现了单去质子化或双去质子化,在芳基方面使用了苯基、4-甲氧基苯基和2-噻吩基,而在4-氯苯基和4-三氟甲基苯基的情况下则实现了双去质子化。实验结果通过DFT B3LYP方法在THF溶液中确定的底物CH酸性进行分析。