Sodium dithionite initiated reactions of Halothane® with enol ethers: Facile synthesis of 3-trifluoromethyl substituted vinyl carbonyl compounds

A convenient and simple method has been found for the preparation of 5,5,5-trifluoro-3-penten-2-one (3) and 4,4,4-trifluorocrotonaldehyde (9) by a sodium dithionite initiated addition of 1-bromo-1-chloro-2,2,2-trifluoroethane to 2-methoxypropene and ethyl vinyl ether, respectively. Reduction of 3 with aluminium isopropoxide afforded allyl alcohol, 5,5,5-trifluoro-3-penten-2-ol (5) and oxidation of 9 gave 4,4,4-trifluorocrotonic acid (11).