1429485-77-7Relevant articles and documents
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.
