Efficient synthesis of N-aryl-aza-crown ethers via palladium-catalyzed amination
N-Aryl-aza-crown ethers were efficiently prepared by reaction of an aza-crown ether with an aryl bromide via a palladium-catalyzed amination. The combination of Pd(2)(dba)(3) and a biphenyl-based electron-rich bulky monophosphine is effective for catalyzing the coupling of 1-aza-15-crown-5 with both electron-deficient and electron-rich aryl bromides under mild conditions. N-Aryl-aza-crown ethers were produced in 75-91% yields. N-Aryl-aza-crown ethers with o-aryl substituents can also be synthesized using this catalyst system, albeit in lower yields ( approximately 40%).
Zhang
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Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Buchwald
SL