Reaction between heterocyclic NH-acids and dibenzoylacetylene in the presence of triphenylphosphine. Simple synthesis of 1-(3-furyl)-1H-imidazole derivatives

The reactive 1:1 intermediate obtained from the addition of triphenylphosphine to dibenzoylacetylene was trapped by heterocyclic NH-acids such as imidazole, 4-nitroimidazole, or 5-methyl-4-nitroimidazole to produce 2,3,5-trisubstituted furan derivatives. Using 2-benzoylimidazole or saccharin as NH-acids leads to enamino ketones. When benzotriazole was employed as NH-acid, both types of products, namely furan derivatives and enamino ketones, were obtained.