135641-61-1Relevant academic research and scientific papers
Effect of Electron-withdrawing Groups on the Thermal Ring Opening of 3H-Pyrazoles to Diazoalkenes
Nakano, Yoshihiko,Ilamaguchi, Masashi,Nagai, Toshikazu
, p. 1701 - 1757 (2007/10/02)
3-Cyano-3H-pyrazoles, bearing a cyano, a p-chlorophenyl, or a p-chlorobenzyl group at C-3, generated from elimination reaction of the corresponding dihydropyrazoles with a leaving group such as a chlorine or p-chlorobenzoyloxy group, gave diazolkene derivatives, resulting from the ring-opening of the 3H-pyrazoles.However, 3-methoxycarbonyl-3H-pyrazoles bearing a methoxycarbonyl, a p-chlorophenyl, or p-chlorobenzyl group at C-3, prepared in a similar manner, gave mainly 1-methoxycarbonyl-1H-pyrazole derivatives, resulting from migration of the 3-methoxycarbonyl group to the adjacent nitrogen within the generated 3H-pyrazoles.Treatment of 3H-pyrazoles (8a and 29b) and 5-substituted 1-methoxycarbonyl-1H-pyrazoles (10a and 31b) with triethylamine gave 3-substituted 1-methoxycarbonyl-1H-pyrazoles, resulting from migration of the methoxycarbonyl group to the remote nitrogen.
