Facile access to imidazole derivatives: carboxylic acids and δ-lactones

The nucleophilic addition of bis-(TMS)ketene acetals to doubly N-activated imidazole under mild conditions, leads to their corresponding dihydroimidazolyl carboxylic acids in a first instance. Subsequent reaction of these acids can be efficiently turned into new bicyclic delta-lactones by a regioselective ring closing procedure promoted by a NBS. Along the work presented herein, the effectiveness of bis-(TMS)ketene acetals as 1,3-carbon-oxygen dinucleophiles was. confirmed in this type of reactions, expanding thus the range of aza-compounds with bicyclic frameworks capable of being built. (C) 2015 Elsevier Ltd. All rights reserved.