Direct amide formation from unactivated carboxylic acids and aminesElectronic supplementary information (ESI) available: Additional experimental information and full characterization and NMR spectra of isolated compounds. See DOI: 10.1039/c1cc15210f

The direct coupling of unactivated carboxylic acids with amines can be performed in toluene 110 C in the absence of catalyst. The use of simple zirconium catalysts at 5 mol% loading gave amide formation in as little as 4 h. Direct amide formation from carboxylic acids and amines has been achieved in as little as 4 h using zirconium catalysts.