Friedel-Crafts acylation of 2(3H)-benzoxazolone: Investigation of the roleof the catalyst and microwave activation

To study the scope and limitations of the use of complexed species of AlCl3 in Friedel-Crafts reactions, we investigated the acetylation and benzoylat ion of 2(3H)-benzoxazolone and 3-methyl-2(3H)-benzoxazolone varying the ami de complexing agent. We replaced dimethylformamide by N-methylformamide, di methylacetamide, pyrrolidone, N-methylpyrrolidone, tetramethylurea, and dim ethylsulfoxide. However, there was no particular advantage of substituting dimethylformamide by another amide ligand. This can probably be ascribed to the fact that the complex formed between AlCl3 and the complexing agent be comes too stable. Alternatively, a route using polyphosphoric acid and micr owave activation was explored. The major advantage of running the reaction in a microwave oven was that a good yield was reached in a rather short per iod of time.