Phosphorazo compounds

For instance, the reaction of amines with carboxylic acids occurs under appreciably milder conditions if phosphorus trichloride is added the reaction does not proceed by way of the intermediate acid chloride, as previously assumed, but the amine and phosphorus trichloride first form a phosphorazo compound (phosphoramidic imide) which in turn reacts with the carboxylic acid to give the amide 693... 

The two steps can be realized separately,693 694 but it is customary to work without isolating the phosphorazo compound. Recently the method has been much used for synthesis of peptides from amino esters and TV-protected amino acids.694-698 Benzene, dioxan, and pyridine are among the solvents used. The technique will be evident from an example ... 

---

See also in sourсe #XX -- [ ]

---