Synthesis of β,β-Difluoro-γ,δ-unsaturated Carboxylic Esters Using Claisen Rearrangement

Claisen rearrangements based on vinyl fluorides

“…Thus, the ester 11b was rearranged according to the general procedure and the crude reaction product was subjected to column chromatography (silica gel) using a mixture of cyclohexane, ethyl acetate and acetic acid (10:1:1) as an eluent. In this way 2-methyl-4-oxododecanoic acid (27) was isolated in 45% overall yield (Scheme 15).…”

“…Among others there are Ireland-Claisen rearrangements with terminal difluorinated allylic esters [23][24][25], JohnsonClaisen rearrangements of allylic alcohols with terminal difluorinated double bonds [24][25][26][27][28], and Claisen rearrangements of polyfluorinated allylvinyl ethers [29][30][31][32][33][34][35]. In contrast, there is a relatively small number of examples for rearrangements with monofluorinated olefins.…”

Synthesis of 2-chloro-1,1-difluoroallyl mesylates through novel rearrangement and CC bond formation by their Pd-catalyzed reaction with diethylzinc

“…We also reported that ethyl 4-chloro-3,3-difluoropent-4-enoates (3) were obtained by the reaction of 2 with triethyl orthoacetate in the presence of a catalytic amount of propanoic acid at 140 8C [5]. This reaction proceeded through the Claisen or [3,3] sigmatropic rearrangement.…”

1-Bromo-1-chloro-2,2,2-trifluoroethane (Halothane) as a building block for fluorine compounds

“…Alcohols 7 were also converted in good yields to b,b-difluorog,d-unsaturated carboxylic esters by the Claisen rearrangement of the corresponding orthoesters and by the reactions with methanesulphonyl chloride to 2-chloro-1,1-difluoroalkenyl mathanesulphonates [12].…”