Preparation and reactions of lithium derivatives of trifluoropropene and trifluoropropyne

1-(Trifluoromethyl)vinyllithium

“…Therefore, there are two different techniques developed for the preparation of 1-(trifluoromethyl)vinyllithium and its reactions with carbonyl compounds. 4 When the carbonyl compound is a gas such as carbon dioxide, 1-(trifluoromethyl)vinyllithium is prepared at −110 • C and the gas is passed into the reaction mixture. 2-Trifluoromethylacrylic acid can be obtained in 56% yield though this process (eq 2).…”

“…With this method, 1-(trifluoromethyl)vinyllithium is immediately formed reacting with carbonyl compounds at around −100 • C. α-(Trifluoroisopropenyl)benzyl alcohol and methylphenyl(trifluoroisopropenyl)carbinol have been synthesized in 32% (eq 3) and 51% (eq 4) yield, respectively, via this procedure. 4 (4) It has been shown that the reaction of 1-(trifluoromethyl)vinyllithium with a carbonyl compound, possessing hydrogen atoms at α-carbon position, affords a general route to substituted butadiene as a dehydration product in high yields by heating with phosphorus pentoxide. 4 For example, treatment of acetone with 1-(trifluoromethyl)vinyllithium reagent affords the corresponding carbinol in 46% yield followed by dehydration with phosphorus pentoxide to furnish 2-methyl-3-(trifluoromethyl)buta-1,3-diene in 49% yield (eq 5).…”

“…4 (4) It has been shown that the reaction of 1-(trifluoromethyl)vinyllithium with a carbonyl compound, possessing hydrogen atoms at α-carbon position, affords a general route to substituted butadiene as a dehydration product in high yields by heating with phosphorus pentoxide. 4 For example, treatment of acetone with 1-(trifluoromethyl)vinyllithium reagent affords the corresponding carbinol in 46% yield followed by dehydration with phosphorus pentoxide to furnish 2-methyl-3-(trifluoromethyl)buta-1,3-diene in 49% yield (eq 5). However, the reaction with trifluoroacetone is abnormal.…”

“…The expected carbinol 1,1,1-trifluoro-2-methyl-3-(trifluoromethyl)but-3-en-2-ol has not been obtained after the reaction of trifluoroacetone with 1-(trifluoromethyl)vinyllithium under several different conditions studied. 4 Instead, mixtures of 1,1,1,5,5,5-hexafluoro-4-hydroxy-4-methylpentan-2-one and a pyran derivative are found due to the cyclization reaction of trifluoroacetone (eq 6). 7 This indicates that 1-(trifluoromethyl)vinyllithium preferentially abstracts a proton from trifluoroacetone rather than attacking the carbonyl function.…”

“…The formation of a (trifluoromethyl)vinyl derivative of silicon has been investigated by the reaction between 1-(trifluoromethyl) vinyllithium and triethylchlorosiliane (eq 7). 4 However, the only product obtained is triethylfluorosilane in a low yield. It shows that possibly fluorine migrates to the silicon atom with elimination of difluoroallene after the initial formation of triethyl(3,3,3-trifluoroprop-1-en-2-yl)silane.…”