title: Synthesis of α-substituted vinylsulfonium salts and their application as annulation reagents in the formation of epoxide- and cyclopropane-fused heterocycles.
abstract: The discovery of new methods for the synthesis of classes of potentially bioactive molecules remains an important goal for synthetic chemists. Vinylsulfonium salts have been used for the synthesis of a wide variety of small heterocyclic motifs; however, further developments to this important class of reagents has been focused on reaction with new substrates rather than development of new vinylsulfonium salts. We herein report the synthesis of a range of α-substituted vinylsulfonium tetraphenylborates (10 examples) in a 3 step procedure from commercially available styrenes. The important role of the tetraphenylborate counterion on the stability and accessibility of the vinylsulfonium salts is also detailed. The α-substituted vinylsulfonium tetraphenylborates gave good to excellent yields in the epoxyannulation of β-amino ketones (15 examples) and the cyclopropanation of allylic amines (4 examples). Hydrogenation of an epoxyannulation product proceeded with good diastereoselectivity.
authors.affiliation: School of Chemistry, University of Bristol , Cantock's Close, BS8 1TS Bristol, U.K.
authors.forename: Johnathan V
authors.initials: JV
authors.lastname: Matlock
authors.forename: Sven P
authors.initials: SP
authors.lastname: Fritz
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Harrison
authors.forename: Diane M
authors.initials: DM
authors.lastname: Coe
authors.forename: Eoghan M
authors.initials: EM
authors.lastname: McGarrigle
authors.forename: Varinder K
authors.initials: VK
authors.lastname: Aggarwal
mesh_terms: D000588:Amines / Q000737:chemistry; D002384:Catalysis; D003521:Cyclopropanes / Q000138:chemical synthesis* / Q000737:chemistry; D004852:Epoxy Compounds / Q000737:chemistry*; D006571:Heterocyclic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D006865:Hydrogenation; D007202:Indicators and Reagents / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry; D012492:Salts / Q000138:chemical synthesis* / Q000737:chemistry*; D013237:Stereoisomerism; D014753:Vinyl Compounds / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D000588:Amines; D003521:Cyclopropanes; D004852:Epoxy Compounds; D006571:Heterocyclic Compounds; D007202:Indicators and Reagents; D007659:Ketones; D012492:Salts; D014753:Vinyl Compounds