Amines As Ligands Promoted Palladium Catalyzed Cross-Coupling Reactions

Palladium-catalyzed Sonogashira cross-coupling reactions of terminal alkynes with aryl halides and Suzuki-Miyaura cross-coupling reaction of aryl halides with organoboronic acids have been recognized as the important methods for the formation of carbon-carbon bonds. The contents of this dissertation mainly include the use of nitrogen-containing compounds such as amines and pyrimidines as ligands for the palladium catalyzed cross-coupling reactions.1. An inexpensive and highly efficient Pd(OAc)2/DABCO catalytic system has been developed for the Sonogashira couplings between aryl halides and terminal alkynes. A combination of Pd(OAc)2 and DABCO (triethylenediamine) was observed to form an excellent catalytic system, which affords high TONs (turnover numbers, up to 720000 TONs for the reaction of p-nitroiodophen and phenylacetylene) for the Sonogashira cross-couplings of aryl iodides and terminal alkynes.2. An efficient and copper-free Sonogashira cross-coupling reaction catalyzed by the Pd(OAc)₂/pyrimidines catalytic system has been described. Aryl iodides and the activated aryl bromine coupled with terminal alkynes were conducted smoothly in moderate to excellent yields using Pd(OAc)2 and 2-aminopyrimidine-4,6-diol as the catalytic system.3. 2-Aminopyrimidine-4,6-diol was found as a stable and efficientligand for the Suzuki-Miyaura cross-couplings of aryl halides with arylboronic acids. In the presence of 3 mol % of Pd(OAc)₂ and 6 mol % of 2-aminopyrimidine-4,6-diol, a variety of ArX (X = I, Br, and Cl) were coupled with arylboronic acids efficiently to offer the corresponding desired products in moderate to excellent yields. Moreover, high TONs (turnover numbers, TONs up to 1 000 000 for the reaction of iodobenzene with phenylboronic acid) for the palladium-catalyzed Suzuki-Miyaura cross-couplings were observed...