An Unusual Cyclization of Trifluoroacetohydroximoyl and -hydrazonoyl Bromides with Malononitrile

Article abstract of DOI:10.1246/bcsj.60.4480

Trifluoroacetohydroximoyl bromide etherate (1) reacted with an excess of malononitrile in the presence of sodium methoxide, giving a fused isoxazolopyridine 3, participated by two molecules of malononitrile, along with the conventional isoxazole 2.Similar concomitant formation of 7 and the fused pyrazolopyridines 8 was also recognized from the hydrazonoyl bromides 6 and their product ratio was found to depend on the reaction conditions, particularly on the concentration of malononitrile used.