Difluoroallylic ethers

Table 7. [2,3] Wittig Rearrangement of 3.3-Difluoroallyl Ethers 23 to Highly...

Reductive defluorination reactions have also been described in ether, difluoroallylic alkoxides undergo stereoselective reduction (Eq. 138) to the E-mono-fluoro derivatives upon treatment with lithium tetrahydridoaluminate [354]. Sodium borohydride [355] and Red-Al [346] have also been used to achieve this transformation. 

Studying [3.3] sigmatropic rearrangements of difluoroallylic alcohols 4 (R = H, Et) under Daubcn-Dictsch conditions [reflux with ethyl vinyl ether in presence of mercury(II) acetate], has shown that in the case of R = Et, besides the rearrangement in situ, elimination of hydrogen fluoride occurs. It has been claimed that the dehydrofluorination is probably catalyzed by acetic acid which is formed in the course of the reaction.206... 

In a 100-mL autoclave containing PhSH (2.2 g, 20 mmol), KOH (110 mg, 2 mmol), and THF (10 mL) cooled to — 78 C, was added 1,1-difluoroallene [(17 2.3 g. 30 mmol) prepared from the reaction of 2-bromo-3.3.3-trifluoroprop-l-ene with BuLi]. The autoclave was then sealed and the mixture was stirred at 60 C for 10 h. After cooling, the solution was poured into EI2O (50 mL) and the ethereal solution was washed to neutrality with brine, and dried (Na SO ). The EtjO was removed under reduced pressure and the residue was distilled to give 3,3-difluoroallyl phenyl sulfide as a liquid yield 3.3 g (89 %) bp 92 C/30 Torr. 

While y-selectivity is usually observed in reaction with substituted allyl halides (e.g., 4-chloro-2-butenyl benzyl ether"), 3-bromo-3,3-difluoro-l-propene behaves differently as the derived allylindium reagent adds to aldehydes like a,ot-difluoroallyl carbanion. ... 

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