An expedient conversion of α-amino acids into Weinreb amides using COMU® as a coupling agent

The use of COMU®, as a non-hazardous partner, in the coupling of N-protected α-amino acids to N-methoxy-N-methylamine to afford the corresponding Weinreb amides is discussed. From a practical point of view the reaction can be monitored visually by virtue of the colour change associated with the conversion of substrates (yellow) into the products (orange). As the by-products of the reaction are conveniently water-soluble the products are isolated relatively pure and with minimal racemisation. These factors coupled with the short reaction time make this a very useful procedure.