SYNTHESIS OF BIS(TRIFLUOROMETHYL)CHROMANOLS

Dimethylhydroquinones (1a-c) were treated with 6-chloro-3-methyl-2-hexen-1-ol in the presence of zinc chloride to give 2-(3-chloropropyl)chromanol derivatives (2a-c), which were methoxymethylated and condensed with trifluoroacetone through the corresponding phosphonium salts (4a-c) to 5,5,5-trifluoro-4-methyl-3-pentenylchromanols (5a-c). 2,5,7-Trimethyl compound (5a) was iodinated and treated with trifluoromethyl iodide and copper powder followed by deprotection and hydrogenation to give 4',8-bis(trifluoromethyl) compound (9a). 4',5-And 4',7-bis(trifluoromethyl) compounds (9b and 9c) were derived from 5b and 5c through bromine compounds.