A METHOD FOR SYNTHESIS OF FLUORINE-COMPOUNDS USING ABNORMAL GRIGNARD REACTION OF HALOTHANE .2. REACTION WITH ALDEHYDES AND UNSATURATED-KETONES

In an abnormal Grignard reaction of halothane, the primary Grignard re agent reacts with another mole of halothane to give 1-bromo-1-chloro-2 ,2,2-trifluoroethylmagnesium bromide, which in turn reacts with a carb onyl compound to give 1-bromo-1-chloro-2,2,2-trifluoroethyl carbinols and their dehalogenation products, 1-chloro-2,2-difluoroethenyl carbin ols. We examined the application of this method to aldehydes and to un saturated ketones. Aldehydes were much less reactive than ketones, and needed higher reaction temperature. However, elevation of temperature caused dehalogenation of the primary products to 1-chloro-2,2-difluor oethenyl derivatives. These derivatives were treated with hydrogen flu oride to afford 1-chloro-1-(trifluoromethyl)ethene derivatives. The re action of cc,P-unsaturated ketones mainly gave 1,2-addition products o f the Grignard reagent, while 3-methyl-2-cyclohexenone gave mainly the 1,4-adducts.