ChemInform Abstract: Reaction of 1‐Substituted Benzimidazoles with Acylacetylenes and Water: Ring‐Opening versus Ring‐Expansion and Isotopic Effect of Deuterium.

Abstract Title compounds (I) react with acylacetylenes (II) and water to give stereoselectively functionalized (Z)‐arylaminovinyl ketones (III), products of imidazole ring‐opening, as main products and benzodiazocinones (IV), products of the imidazole ring‐expansion, as side‐products.