Trifluoromethyl substitution affects the regiochemistry of cyclising condensation in 1,4 substitution processes
摘要:
Beta-Trifluoromethyl beta-chloroacrolein 2 reacts with 2-mercaptoethylamine 3 to produce thiazolidine 5 instead of the expected thiazepine 8. The reason of this behaviour is the formation of the tetrahedral intermediate 6 because of stabilisation by the trifluoromethyl group ; an intramolecular substitution takes place faster than a 1,4 addition-elimination process.