Unexpected trifluoromethylated pyrazoles from ethyl 2-diazo-4,4,4-trifluoroacetoacetate and 1-diethylamino-prop-1-yne

Article abstract of DOI:10.1016/0022-1139(94)03081-2

Ethyl 2-diazo-4,4,4-trifluoroacetoacetate reacts with N,N-diethylamino-prop-1-yne via an unusual pathway: the ynamine first reacts with the carbonyl adjacent to CF3, leading to a non-isolated vinyldiazomethane, which undergoes intramolecular cyclisation and then a <1,5>-shift to afford a pyrazole. - Keywords: Trifluoromethylated pyrazoles; Intramolecular cyclisation; Ynamine reaction; NMR spectroscopy; IR spectroscopy