Role of the Base in Buchwald鈥揌artwig Amination
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- 作者：Ylva Sunesson ; Elaine Lim茅 ; Sten O. Nilsson Lill ; Rebecca E. Meadows ; Per-Ola Norrby
- 刊名：Journal of Organic Chemistry
- 出版年：2014
- 出版时间：December 19, 2014
- 年：2014
- 卷：79
- 期：24
- 页码：11961-11969
- 全文大小：476K
- ISSN：1520-6904
文摘
The Buchwald鈥揌artwig amination has been investigated theoretically and experimentally to examine the scope of possible bases under different reaction conditions. Nonpolar solvents resist the formation of new charges. Therefore, the base should be anionic to be able to deprotonate the neutral palladium鈥揳mine complex and/or expel the anionic leaving group (bromide). The calculated barrier for the organic base DBU was found to be prohibitively high. In polar solvent, dissociation of bromide becomes possible, but here the base will instead form a complex with palladium, creating an overly stable resting state. The conclusions for both solvent classes hold for both a hindered monodentate phosphine and the labile bidentate ligand BINAP. The computational studies were supported by experimental testing of a range of bases using BINAP in two different solvents, toluene and DMF.