The conversion of 3-acyl-4-hydroxycoumarins to either 4-oxo-1-phenyl-1H-[1]benzopyrano[4,3-c]pyrazoles or 4-oxo-2-phenyl-2H-[1]benzopyrano[4,3-c]pyrazoles is described. The product obtained from the reaction of phenylhydrazine with 3-chromonecarboxylic acid has been established not to be such 2-phenyl[1]benzopyrano[4,3-c]pyrazol-3-2H-one as previously reported but to be 4-oxo-1-phenyl-1H[1]benzopyrano[4
3-酰基-
4-羟基
香豆素转化为4-氧代-1-苯基-1H- [1]苯并
吡喃并[4,3-c]
吡唑或4-氧代-2-苯基-2H- [1]苯并
吡喃[描述了4,3-c]
吡唑。已经确定由苯
肼与3-色
酮羧酸反应获得的产物不是先前报道的2-苯基[1]苯并
吡喃并[4,3-c]
吡唑-3-2H-酮,而是4-氧代。 -1-苯基-1H [1]苯并
吡喃并[4,3-c]
吡唑。我们的结果表明,以前描述为从4-
氯-3-甲酰基-
香豆素中收率的方法是不可行的。