1: With acetic acid in tetrahydrofuran 8 h; Inert atmosphereReflux; 2: With acetyl chloride in tetrahydrofuran Knorr Pyrazole Synthesis; 8 h; Inert atmosphereReflux; regioselective reaction;

in ethanol Heating;

1.1: lithium tert-butylate / tetrahydrofuran / 4 h / 0 - 20 °C / |Inert atmosphere 2.1: acetic acid / tetrahydrofuran / 8 h / |Inert atmosphere; |Reflux 2.2: 8 h / |Inert atmosphere; |Reflux View Scheme

ethanol; acetic acid

1: ethanolic KOH View Scheme