Three-component synthesis of highly functionalized 5-acetyloxazoles.

By a flexible three-component synthesis, alkoxy-substituted enamides are easily available from lithiated alkoxyallenes, nitriles and carboxylic acids (see scheme). The treatment of these versatile intermediates with trifluoroacetic acid provided 5-acetyloxazoles in moderate to good yields. Different substituents are possible at C-2 and C-5 and the 5-acetyl group is a suitable handle for further synthetic transformations.