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.
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).
Bunescu
Alina
A
Institut für Chemie, Universität Rostock, Albert-Einstein-Strausse 3a, 18059 Rostock, Germany.
Reimann
Sebastian
S
Lubbe
Mathias
M
Spannenberg
Anke
A
Langer
Peter
P
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*
C543753:4,4-dimethoxy-1,1,1-triflorobut-3-en-2-one; D006845:Hydrocarbons, Fluorinated; D008024:Ligands; D011714:Pyrans; D005461:Fluorine; D008697:Methane