Aceticanhydride mediates a facile and rapid condensation of benzimidazole with aromatic o-diacid dichlorides to precipitate p-dione adducts in excellent yields. Condensation with pyridine-3,4-dicarbonyl dichloride produced a 1:1 mixture of isomeric p-diones. The X-ray crystal structure of one of the latter isomers revealed unusual high density, and inter-layer separation similar to graphite. Cyclic
Acetic Anhydride Generated Imidazolium Ylide in Ring Closures onto Carboxylic Acids; Part of the Synthesis of New Potential Bioreductive Antitumor Agents
作者:Fawaz Aldabbagh、Eamonn Joyce、Patrick McArdle
DOI:10.1055/s-0030-1260543
日期:2011.5
Acetic anhydride behaves as a traceless activating agent allowing thermal intramolecular condensation of 2-(benzimidazol-1-ylmethyl) benzoic and nicotinic acids. Autoxidation gives benzimidazo[1,2-b]isoquinoline-6,11-diones (intermediates characterized) and benzimidazo[2,1-g]-1,7-naphthyridine-5,12-diones in a facile, one-pot transformation. The 1,4-dimethoxy analogue of the former is converted into