title: Synthesis of trifluoromethyl-substituted arenes, cyclohexenones and pyran-4-ones by cyclocondensation of 1,3-bis(silyloxy)-1,3-butadienes with 4,4-dimethoxy-1,1,1-trifluorobut-3-en-2-one: influence of the lewis acid on the product distribution.
abstract: The TiCl(4)-mediated formal [3 + 3] cyclocondensation of 1,3-bis(trimethylsilyloxy)-1,3-butadienes with 4,4-dimethoxy-1,1,1-trifluorobut-3-en-2-one afforded a variety of functionalized 4-methoxy-6-(trifluoromethyl)salicylates and 3-methoxy-5-(trifluoromethyl)phenols with very good regioselectivity. The Me(3)SiOTf-mediated cyclization of 1,3-bis(trimethylsilyloxy)-1,3-butadienes, containing no substituent located at carbon atom C-4 of the diene (R(1) = H), resulted in the formation of trifluoromethyl-substituted pyran-4-ones. In contrast, trifluoromethylated cyclohexenones were formed when dienes were employed which do contain a substituent located at carbon C-4 (R(1) not equal H).
authors.affiliation: Institut für Chemie, Universität Rostock, Albert-Einstein-Strausse 3a, 18059 Rostock, Germany.
authors.forename: Alina
authors.initials: A
authors.lastname: Bunescu
authors.forename: Sebastian
authors.initials: S
authors.lastname: Reimann
authors.forename: Mathias
authors.initials: M
authors.lastname: Lubbe
authors.forename: Anke
authors.initials: A
authors.lastname: Spannenberg
authors.forename: Peter
authors.initials: P
authors.lastname: Langer
mesh_terms: D002626:Chemistry, Pharmaceutical; D003500:Cyclization; D005461:Fluorine / Q000737:chemistry*; D006845:Hydrocarbons, Fluorinated / Q000737:chemistry*; D008024:Ligands; D008697:Methane / Q000737:chemistry*; D015394:Molecular Structure; D011714:Pyrans / Q000737:chemistry*
chemical_list: C543753:4,4-dimethoxy-1,1,1-triflorobut-3-en-2-one; D006845:Hydrocarbons, Fluorinated; D008024:Ligands; D011714:Pyrans; D005461:Fluorine; D008697:Methane