Switchable Reactivity: The Site-Selective Functionalization of Trifluoromethyl-Substituted Pyrazoles
作者:Manfred Schlosser、Jean-Noël Volle、Frédéric Leroux、Kurt Schenk
DOI:10.1002/1099-0690(200209)2002:17<2913::aid-ejoc2913>3.0.co;2-d
日期:2002.9
materials into families of isomers and congeners. Depending on the choice of the reagent, 1-methyl-5-(trifluoromethyl)pyrazole undergoes deprotonation and subsequent carboxylation mainly or exclusively at either the 4-position of the heterocycle or at the nitrogen-attached Me group. Similarly, 1-phenyl-5-(trifluoromethyl)pyrazole and 3-methyl-1-phenyl-5-(trifluoromethyl)pyrazole are selectively attacked
现代有机金属方法能够将简单的杂环起始材料区域灵活地转化为异构体和同系物家族。取决于试剂的选择,1-甲基-5-(三氟甲基)吡唑主要或仅在杂环的4-位或在氮连接的Me基团上经历去质子化和随后的羧化。类似地,1-苯基-5-(三氟甲基)吡唑和3-甲基-1-苯基-5-(三氟甲基)吡唑在杂环4-位被二异丙基氨基锂选择性攻击,在4-位被丁基锂和Ph 环的正交位置。相比之下,1-甲基-3-(三氟甲基)吡唑的金属化仅发生在 5 位,无论是有机金属碱还是金属氨化物碱。如果将溴引入杂环或芳基中,则其他位点可进行功能化。戒指。4-溴-1-甲基-5-(三氟甲基)吡唑、4-溴-1-甲基-3-(三氟甲基)吡唑、4-溴-1-甲基-5-(三氟甲基)吡唑和1-(2-溴苯基)-5-(三氟甲基)吡唑。[在 SciFinder (R) 上]