Novel synthesis of 1-aryl-1-trifluoromethylallenes

3,3-Bis(phenylthio)-1,1,1,2,2-pentafluorobutane 1 was reacted with aryllithium reagents (6 equiv) in ether at low to room temperature for 1–6 h to provide 2-aryl-1,1,1-trifluoro-3-phenylthio-2-butene 2 in 80–96% yields. Bromination of 2 with NBS in acetonitrile at reflux for 1–7 h afforded the corresponding allylic bromides 3 in 61–96% yields. Treatment of 3 with MCPBA (1.5 equiv) in methylene chloride at reflux temperature for 1–12 h resulted in the formation of 1-aryl-1-trifluoromethylallenes 4 in 74–96% yields.