title: Stereoselective Synthesis of Trisubstituted Vinyl Bromides by Addition of Alkynes to Oxocarbenium Ions.
abstract: We have developed an efficient method for the synthesis of (E)-trisubstituted vinyl bromides via a Friedel-Crafts-type addition of alkynes to oxocarbenium ions formed in situ from acetals. The success of this reaction relies on identification of MgBr2·OEt2as both a Lewis acid promoter and bromide source. This reaction employs simple, inexpensive starting materials and proceeds under mild conditions to allow the preparation of a range of vinyl bromide products in high yields and E:Z selectivities. Furthermore, the vinyl bromide products also contain an allylic ether functional group. Both the vinyl bromide and allylic ether are effective handles for the elaboration of these useful synthetic intermediates.
authors.affiliation: Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States.
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Ehle
authors.affiliation: Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States.
authors.forename: Melissa G
authors.initials: MG
authors.lastname: Morris
authors.affiliation: Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States.
authors.forename: Bryan D
authors.initials: BD
authors.lastname: Klebon
authors.affiliation: Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States.
authors.forename: Glenn P A
authors.initials: GP
authors.lastname: Yap
authors.affiliation: Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States.
authors.forename: Mary P
authors.initials: MP
authors.lastname: Watson
keywords: Friedel–Crafts; alkyne; oxocarbenium ion; stereoselective; trisubstituted vinyl bromide; vinylation