Syntheses, oxidations, and palladium complexes of fluorous dialkyl sulfides: new precursors to highly active catalysts for the Suzuki coupling
- Additional Document Info
- View All
Reactions of Rf8(CH2)nI (Rf8=CF3(CF2)7) with Li2S give the fluorous dialkyl sulfides (Rf8(CH2)n)2S (n=2, 1, 71%; 3, 2, 67%) as low melting white solids that are soluble in most fluorous and organic solvents. Reactions of 1 and 2 with CH3CO3H yield the corresponding sulfoxides (Rf8(CH2)n)2S=O (85; 80%), which are soluble in CF3C6F5 at room temperature, but insoluble in most other solvents. At higher temperatures, solubilities can become appreciable. Reactions of 1 and 2 with Na2PdCl4 (ca. 0.5equiv.) give palladium complexes [(Rf8(CH2)n)2S]2PdCl 2 (5, 94%; 6, 95%), which are soluble in only a limited range of fluorinated solvents at room temperature. The CF3C6F11/toluene partition coefficients of 1 and 2 are 98.7:1.3 and 96.6:3.4 (24°C). The Suzuki coupling of aryl bromides and PhB(OH)2 to biaryls is catalyzed by 5 and 6 (0.02mol%) in CF3C6F11/DMF/H2O in the presence of K3PO4, generally at room temperature. Turnover numbers of 4500-5000 are easily achieved. However, activities decrease under fluorous biphase recycling conditions, and implications for the nature of the catalytically active species are discussed. © 2002 Elsevier Science Ltd. All rights reserved.
author list (cited authors)
Rocaboy, C., & Gladysz, J. A.