SCHEDULED MAINTENANCE
Stereoselective synthesis of (Z)-methyl 3-perfluoroalkyl-4-substitutedphenylbutenoates
Abstract
The stereoselective synthesis of (Z)-methyl 3-perfluoroalkyl-4-substituted-phenylbut-3-enoates 8a–o has been investigated. The reaction of substituted benzyltriphenylphosphonium bromides 5a–e with methyl 2-perfluoroalkylnoates 2a–c in the presence of K2CO3 at room temp. gives two adducts, methyl 3-perfluoroalkyl-4-substituted-phenyl-2-triphenylphosphoranylidenebut-3-enoates, 6a–o and methyl 3-perfluoroalkyl-4-substituted-phenyl-4-triphenylphosphoranylidenebut-2-enoates, 7a–o. Compounds 6a–o exists as pairs of E/Z isomers, the ratios are 2 : 1 for RF= CF3, and 3 : 1 for RF= C2F5 or C3F7. Compounds 7a–o are transformed into 6a–o when heated. (Z)-Methyl 3-perfluoroalkyl-4-substituted-phenylbut-3-enoates 8a–o can be obtained stereoselectively in high yield when an aqueous methanol solution of mixed 6a–o and 7a–o was heated for 10–20 h.
Please wait while we load your content...
