One-pot transition-metal-free synthesis of Weinreb amides directly from carboxylic acids was written by Niu, Teng;Wang, Ke-Hu;Huang, Danfeng;Xu, Changming;Su, Yingpeng;Hu, Yulai;Fu, Ying. And the article was included in Synthesis in 2014.Recommanded Product: 106675-70-1 This article mentions the following:
Weinreb amides were prepared directly from carboxylic acids, N,O-dimethylhydroxylamine, and phosphorus trichloride in one pot at 60° in toluene in high yields, thus avoiding the separation of the moisture and air sensitive intermediate P[NMe(OMe)]3 in advance. Sterically hindered carboxylic acids also give the corresponding Weinreb amides in excellent yields. Various functional groups are tolerated on the carboxylic acid. The method, which is a simple process and gives high yields, is suitable for large-scale production In the experiment, the researchers used many compounds, for example, N1,N2-Dimethoxy-N1,N2-dimethyloxalamide (cas: 106675-70-1Recommanded Product: 106675-70-1).
N1,N2-Dimethoxy-N1,N2-dimethyloxalamide (cas: 106675-70-1) belongs to amides. Because of the greater electronegativity of oxygen, the carbonyl (C=O) is a stronger dipole than the N–C dipole. The presence of a C=O dipole and, to a lesser extent a N–C dipole, allows amides to act as H-bond acceptors. Amides can be recrystallised from large quantities of water, ethanol, ethanol/ether, aqueous ethanol, chloroform/toluene, chloroform or acetic acid. The likely impurities are the parent acids or the alkyl esters from which they have been made. The former can be removed by thorough washing with aqueous ammonia followed by recrystallisation, whereas elimination of the latter is by trituration or recrystallisation from an organic solvent.Recommanded Product: 106675-70-1
Referemce:
Amide – Wikipedia,
Amide – an overview | ScienceDirect Topics