N–H Insertion reactions of rhodium carbenoids. Part 5: A convenient route to 1,3-azoles

Dirhodium(II) carboxylate catalysed reaction of diazocarbonyl compounds in the presence of primary amides results in the formation of α-acylaminoketones (12 examples) by N–H insertion reaction of the intermediate rhodium carbene. The 1,4-dicarbonyl compounds are readily converted into structurally diverse oxazoles (11 examples) by cyclodehydration, thiazoles (10 examples) by treatment with Lawessonʹs reagent, or imidazoles (2 examples) by reaction with ammonia or methylamine.