Highly efficient and environmentally benign preparation of Weinreb amides in the biphasic system 2-MeTHF/water

A straightforward chromatography-free preparation of Weinreb amides starting from acid halides has been achieved in the biphasic medium 2-MeTHF/water. Analytically pure compounds were isolated in excellent yields simply after removal of 2-MeTHF, which absolutely avoids the use of any contaminant organic solvent within the whole process due to its (practically) immiscibility with water.