Acetic Acid → methyl [(4E)-1-(2-chlorophenyl)-4-(1-ethoxyethylidene)-5-oxo-4,5-dihydro-1H-pyrazol-3-yl]acetate

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Reaction Conditions

Reaction Steps

The mixture of the above obtained methyl[1-(2-chlorophenyl)-5-hydroxy-1H-pyrazol-3-yl]acetate (Compound of Formula (IV), 1.00 g), glacial acetic acid (21 μl, 0.1 equiv.) and MeC(OEt)3 (2.00 ml) was heated at 60° C. for 1 h 15. The resulting red solution was concentrated in vacuo to afford a red syrup that was washed with cyclohexane and then dried in vacuo. Due to its relative instability, no further purification of methyl[(4E)-1-(2-chlorophenyl)-4-(1-ethoxyethylidene)-5-oxo-4,5-dihydro-1H-pyrazol-3-yl]acetate was conducted (1.26 g, quantitative yield). MS (ESI+): 336.8; MS (ESI−): 334.6.

Provenance & Evidence