| 초록 |
2,2-Difluoro-1-arylethenylsilanes 3 are useful building blocks for the synthesis of gem-difluorinated alkenes. However, previous methods for the preparation of 3 have been quite limited. A simple and straight forward approach to compound 3 will be established by the palladium-catalyzed cross-coupling of the 2,2-difluoro-1-trialkylsilylethenyl tosylate 2 with arylboronic acids. Starting material 2 was prepared in 83% yield from the reaction of 2,2,2-trifluoroethyl tosylate 1 with 2.2 equiv of LDA in THF at -78 ℃ for 1 h, followed by treatment with 1.0 equiv of (t-butyl)dimethylsilyl chloride. The cross-coupling reaction of 2 with arylboronic acids in the presence of 10 mol% Pd2(dba)3, 20 mol% SPhos and 1.7 equiv of Cs2CO3 in dioxane : H2O (10:1) at 100 ℃ for 3-10 hours provided the compounds 3 in good yields. Acylation of 3 with benzoyl chloride in presence of AlCl3 afforded the addition products 4 in good yields. The scope and limitation of these reactions will be presented. |
