Claisen rearrangements based on vinyl fluorides

Synthesis of optically active 2-fluoroalk-1-en-3-yl esters and chirality transfer in their Claisen-type rearrangements

“…Thus, the Johnson-Claisen rearrangement of 2-fluoroalk-1-en-3-ols with triethyl orthoacetate gave ethyl 4-fluoroalk-4-enoates in high yield [9]. Moreover, the Irelend-Claisen rearrangement of a-substituted acetic acid esters of the mentioned fluorinated allylic alcohols such as achloroacetic esters or propionic esters, led to the corresponding 2-substituted 4-fluoroalk-4-enoic acids in moderate yields [9].…”

“…Thus, the Johnson-Claisen rearrangement of 2-fluoroalk-1-en-3-ols with triethyl orthoacetate gave ethyl 4-fluoroalk-4-enoates in high yield [9]. Moreover, the Irelend-Claisen rearrangement of a-substituted acetic acid esters of the mentioned fluorinated allylic alcohols such as achloroacetic esters or propionic esters, led to the corresponding 2-substituted 4-fluoroalk-4-enoic acids in moderate yields [9]. The reaction was shown to work also with N-protected glycine esters to give 2-amino-4-fluoroalk-4-enoic acids in excellent yields in a modified Kazmaier variation [10] of the IrelandClaisen rearrangement [11].…”

Synthesis of γ-fluoro-α-amino acids by Claisen rearrangement

“…Solvents for chromatography were distilled prior to use. The fluorinated allylalcohols were prepared as described recently [75]. The N-protected amino acids are commercially available.…”

“…Different examples of Johnson-Claisen rearrangements of 2-fluoroallyl alcohols [74,75] and 3-fluoroallyl alcohols [76,77] have been published. This reaction has also been used as a key-step in nucleoside syntheses [78][79][80].…”

“…This reaction has also been used as a key-step in nucleoside syntheses [78][79][80]. Recently, we reported several examples of Ireland-Claisen rearrangements of 2-fluoroalyllic esters to form g-fluoro-g,d-unsaturated carboxylic acid esters [75].…”