The reaction of biscarbamoyl diselenides with aromatic compounds in the presence of Lewis acids resulted in Friedel-Crafts type carbamoylation (Gatterman amide synthesis) to give corresponding aromatic amides in good yields. This methodology was successfully applied to aroylation and benzylation by use of dibenzoyl diselenide and dibenzyl diselenide, respectively.
Synthesis of Isochalcogenazole Rings by Treating β-(<i>N</i>,<i>N</i>-Dimethylcarbamoylchalcogenenyl)alkenyl Ketones with Hydroxylamine-<i>O</i>-sulfonic Acid
β-(N,N-Dimethylcarbamoylselenenyl)- and β-(N,N-dimethylcarbamoyltellurenyl)alkenyl ketones were converted into isoselenazoles and isotellurazole Te-oxides, respectively, simply by treating with hydroxylamine-O-sulfonic acid, and deoxygenation of the latter products was successfully carried out by treating with PPh3. Alternative treatment of ynone oxime tosylates with hydrochalcogenide ions or N,N-dimethylchalcogenocarbamate ions also gave the same isochalcogenazole rings. These reactions were assumed to proceed through intramolecular nucleophilic substitution on the nitrogen atom of oxime sulfonates by the attack of in situ generated chalcogen nucleophiles.
Cesium Salt-Catalyzed Addition of Diphenyl Dichalcogenides to Alkynes: Selective Synthesis of Bis- and Mono(phenylchalcogeno)alkenes
作者:Yutaka Nishiyama、Haruko Ohnishi、Yuya Koguma
DOI:10.1246/bcsj.82.1170
日期:2009.9.15
A cesium salt has a unique catalytic ability for the reaction of alkynes with diphenyl dichalcogenides. When the diphenyl dichalcogenides, such as the disulfide, diselenide, or ditelluride, were allowed to react with alkynes in the presence of a catalytic amount of a cesium fluoride or carbonate, the bisphenylchalcogenolation of the alkynes efficiently proceeded to give the corresponding vic-bis(phenylchalcogeno)alkenes in moderate to good yields with high selectivity. When H2O was added to the reaction medium, monophenylchalcogenolation of the alkynes occurred giving the mono(phenylchalcogeno)alkenes in moderate yields.