1429485-75-5Relevant academic research and scientific papers
Solvent- and transition metal catalyst-dependent regioselectivity in the [3+2]cyclocondensation of trifluoromethyl-α,β-ynones with hydrazines: Switchable access to 3- and 5-trifluoromethylpyrazoles
Hsieh, Min-Tsang,Kuo, Sheng-Chu,Lin, Hui-Chang
, p. 683 - 689 (2015/03/18)
The regioselectivity of the [3+2]cyclocondensation of trifluoromethyl-α,β-ynones with hydrazines can be readily tuned to preferentially afford either 3- or 5-trifluoromethylpyrazoles through variation of the reaction conditions. Under catalysis with copper(II) acetate (2.0 mol%), cyclocondensation proceeded smoothly to yield 3-trifluoromethylpyrazoles with high regioselectivity. In contrast, when the reaction was conducted in dimethyl sulfoxide under catalyst-free conditions, the formation of 5-trifluoromethylpyrazoles was predominantly observed.
Synthesis of 4-fluoromethylsydnones and their participation in alkyne cycloaddition reactions
Foster, Robert S.,Adams, Harry,Jakobi, Harald,Harrity, Joseph P. A.
, p. 4049 - 4064 (2013/06/05)
We report the synthesis and some structural studies of 4-trifluoromethyl, 4-difluoromethyl-, and 4-monofluoromethylsydnones. All but the latter compounds are stable and represent effective precursors to a range of pyrazoles after cycloaddition reactions with alkynes. The cycloadditions are generally highly regioselective and provide 5-fluoromethylpyrazole products, although we have observed that Bn-substituted sydnones can provide an unexpected alkyne insertion mode that generates the 3-fluoromethyl isomer.
