title: Catalytic anti-Markovnikov hydrobromination of alkynes.
abstract: We have developed the first catalytic method for anti-Markovnikov hydrobromination of alkynes. The reaction affords terminal E-alkenyl bromides in high yield and with excellent regio- and diastereoselectivity. Both aryl- and alkyl-substituted terminal alkynes can be used as substrates. Furthermore, the reaction conditions are compatible with a wide range of functional groups, including esters, nitriles, epoxides, aryl boronic esters, terminal alkenes, silyl ethers, aryl halides, and alkyl halides. A preliminary study of the reaction mechanism suggests that the hydrobromination reaction involves hydrocupration of an alkyne, followed by the bromination of the alkenyl copper intermediate. This study also suggests that 2-tert-butyl potassium phenoxide functions as a mild catalyst turnover reagent and provides a better understanding of the unique effectiveness of (BrCl2C)2 among brominating reagents.
authors.affiliation: Department of Chemistry, University of Washington , Seattle, Washington 98195, United States.
authors.forename: Mycah R
authors.initials: MR
authors.lastname: Uehling
authors.forename: Richard P
authors.initials: RP
authors.lastname: Rucker
authors.forename: Gojko
authors.initials: G
authors.lastname: Lalic