title: Isoselenazolones as catalysts for the activation of bromine: bromolactonization of alkenoic acids and oxidation of alcohols.
abstract: Isoselenazolones were synthesized by a copper-catalyzed Se-N bond forming reaction between 2-halobenzamides and selenium powder. The catalytic activity of the various isoselenazolones was studied in the bromolactonization of pent-4-enoic acid. Isoselenazolone 9 was studied as a catalyst in several reactions: the bromolactonization of a series of alkenoic acids with bromine or N-bromosuccinimide (NBS) in the presence of potassium carbonate as base, the bromoesterification of a series of alkenes using NBS and a variety of carboxylic acids, and the oxidation of secondary alcohols to ketones using bromine as an oxidizing reagent. Mechanistic details of the isoselenazolone-catalyzed bromination reaction were revealed by (77)Se NMR spectroscopic and ES-MS studies. The oxidative addition of bromine to the isoselenazolone gives the isoselenazolone(IV) dibromide, which could be responsible for the activation of bromine under the reaction conditions. Steric effects from an N-phenylethyl group on the amide of the isoselenazolone and electron-withdrawing fluoro substituents on the benzo fused-ring of the isoselenazolone appear to enhance the stability of the isoselenazolone as a catalyst for the bromination reaction.
authors.affiliation: Department of Chemistry,  Indian Institute of Science Education and Research Bhopal  (IISER), Bhopal, Madhya Pradesh 462 023, India.
authors.forename: Shah Jaimin
authors.initials: SJ
authors.lastname: Balkrishna
authors.forename: Ch Durga
authors.initials: ChD
authors.lastname: Prasad
authors.forename: Piyush
authors.initials: P
authors.lastname: Panini
authors.forename: Michael R
authors.initials: MR
authors.lastname: Detty
authors.forename: Deepak
authors.initials: D
authors.lastname: Chopra
authors.forename: Sangit
authors.initials: S
authors.lastname: Kumar