title: β-(Trifluoromethyl)vinyl sulfonium salts: preparation and reactions with active methylene and methenyl compounds.
abstract: Two trifluoromethyl-substituted building blocks β-(trifluoromethyl)vinyl sulfonium salts 1 and 2 were developed. Reactions of β-(trifluoromethyl)vinyl sulfonium salt 1 with active methylene compounds containing electron-withdrawing groups using DBU as the base in DMSO occurred to give trifluoromethyl-substituted cyclopropane derivatives 7 as the major products. In contrast, reactions of β-(trifluoromethyl)vinyl sulfonium salt 2 with active methylene compounds occurred with the migration of one of the electron-withdrawing groups to give the products 8 as the major products when NaH was used as the base in DMSO. Moreover, when NaH was used as base in THF/CH(2)Cl(2) at -78 °C, reaction of β-(trifluoromethyl)vinyl sulfonium salt 1 gave trifluoromethyl-substituted 2,3-dihydrofuran derivatives 9 as the major products. A working mechanism was proposed to explain the different behaviors of the β-(trifluoromethyl)vinyl sulfonium salts 1 or 2 with active methylene compounds under these different conditions.
authors.affiliation: Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, People's Republic of China.
authors.forename: Hao
authors.initials: H
authors.lastname: Lin
authors.forename: Qilong
authors.initials: Q
authors.lastname: Shen
authors.forename: Long
authors.initials: L
authors.lastname: Lu