title: Synthesis of Diaryl Ethers, Diaryl Thioethers, and Diarylamines Mediated by Potassium Fluoride-Alumina and 18-Crown-6: Expansion of Scope and Utility(1).
abstract: An efficient alternative to the Ullmann ether synthesis of diaryl ethers, diaryl thioethers, and diarylamines involving the S(N)Ar addition of a phenol, thiophenol, or aniline to an appropriate aryl halide, mediated by potassium-fluoride alumina and 18-crown-6 in acetonitrile or DMSO, is described. Expansion of the reaction conditions to include DMSO as solvent has resulted in a far greater range of substitution patterns permitted on the electrophile. For example, it was found that electronically unfavorable 3-chlorobenzonitrile could be condensed with 3-methoxyphenol to form the corresponding diaryl ether in 66% yield, a combination not normally amenable to Ullmann coupling. Electron-withdrawing groups present on the electrophile may be as diverse as nitro, cyano, formyl, acetyl, ester, amide, and even aryl. The method features a simple reaction procedure that provides products in generally good to excellent purified yields.
authors.affiliation: The Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana 46285.
authors.forename: J. Scott
authors.initials: JS
authors.lastname: Sawyer
authors.forename: Elisabeth A.
authors.initials: EA
authors.lastname: Schmittling
authors.forename: Jayne A.
authors.initials: JA
authors.lastname: Palkowitz
authors.forename: William J.
authors.initials: WJ
authors.lastname: Smith