The reaction of acyl halides with diazoacetic esters to give acyldiazoacetic esters is well known. However, benzoyl bromide appears to be the sole example of an aroyl halide undergoing this reaction. 6 The het, erocycles, furoyl bromide and chloride, react with methyl diazoacetate (I) to give methyl (a-furoy1) diazoacetate in 80% and unstated yields, respectively.'Our attempts to extend this reaction led to carboxylic anhydrides and an 0- ...