Synthesis of 2-Acylselenophenes via Iodine-Promoted Nucleophilic Cyclization of [2-(Butylselanyl)phenyl]-propynols

We describe the synthesis of [2-(butylselanyl)phenyl]propynols and their application as substrates in intramolecular iodine-promoted nucleophilic cyclization reactions for the preparation of 2-acylselenophenes. [2-(Butylselanyl)phenyl]propynols were prepared by nucleophilic aromatic substitution reactions of 2-halobenzaldehydes with lithium butylselenolate followed by alkynylation of the carbonyl function with lithium acetylides. Effects of solvent, temperature, reaction time and iodine amount on the efficiency of the cyclization reactions were investigated. The results demonstrated that the best yields of 2-acylselenophenes were obtained when iodine (1.1 equiv.) and ethanol (3 mL) at room temperature were applied to [2-(butylselanyl)phenyllpropynols. The utility of 2-acylselenophene derivatives was also studied through alkynylation of a carbonyl group to obtain the alkynol derivatives followed by an electrophilic cyclization reaction to give selenophene-fused aromatic compounds. The 2-acylselenophene was also applied as a substrate in cyanation reactions.