Improved Functional Group Compatibility in the Palladium-Catalyzed Amination of Aryl Bromides

✍ Scribed by John P Wolfe; Stephen L Buchwald

• Publisher: Elsevier Science
• Year: 1997
• Tongue: French
• Weight: 430 KB
• Volume: 38
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(97)01463-9

✦ Synopsis

Aryl bromides are coupled with arnines in the presence of a palladium catalyst and a stoichiometric amount of cesium carbonate. Using these conditions base-sensitive functional groups, which were incompatible with our previously reported catalytic-amination reaction conditions, are well tolerated. 0 1997 Elsevier ScienceLtd.

Work from our laboratory and that of Hartwig has documented that the palladium-l and nickelcatalyzedlc formation of anilines from aryl halides and triflates is a process with wide scope. We were frustrated, however, by the lack of tolerance of the reaction protocols for a number of common functional groups. Our work indicated that sodium t-butoxide, the most effective base for most procedures, was the source of much of the problem. We recently reported that (rac)-PPF-0Me2 was a superior Iigand for arninations with acyclic secondary arnines.ld Our working hypothesis suggested that the intermediate palladium complex was less electron-rich than analogous complexes formed when chelating bis-phosphines were employed. We felt that the amine adduct I, a presumed intermediate, might be relatively acidic and, hence, the reaction might proceed with weaker bases.