One-Pot Transition-Metal-Free Synthesis of Weinreb Amides Directly from Carboxylic Acids
Teng Niu, Ke-Hu Wang, Danfeng Huang*, Changming Xu, Yingpeng Su, Yulai Hu*, Ying Fu
*College of Chemistry and Chemical Engineering, Northwest Normal University, Anning Road 967 (E), Lanzhou 730070, P. R. of China, Email: huangdfnwnu.edu.cn, huylnwnu.edu.cn
T. Niu, K.-H. Wang, D. Huang, C. Xu, Y, Su, Y. Hu, Y. Fu, Synthesis, 2014, 46, 320-330.
DOI: 10.1055/s-0033-1340317 (free Supporting Information)
Weinreb amides can be prepared directly from carboxylic acids and N,O-dimethylhydroxylamine in the presence of phosphorus trichloride at 60°C in toluene without separation of the moisture and air sensitive intermediate P[NMe(OMe)]3. Various functional groups are tolerated and even sterically hindered carboxylic acids give the corresponding Weinreb amides in excellent yields. The method is suitable for large-scale production.
see article for more examples
T. Niu, W. Zhang, D. Huang, C. Xu, H. Wang, Y. Hu, Org. Lett., 2009, 11, 4474-4477.
Weinreb amides, carboxylic acids, one-pot reaction, coupling, synthesis