ABSTRACT Aqueous solution of boric acid, as an efficient and green catalytic system, was efficiently utilized tandem four-component condensation reaction of aryl aldehydes with ethyl acetoacetate, malononitrile, and hydrazine hydrate to give pyranopyrazole derivatives. By the reaction of boric acid with water, H+ was prepared and efficiently catalyzed the reaction under mild and green condition.

中文翻译：

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使用水中硼酸作为高效绿色催化体系的芳基醛与乙酰乙酸乙酯、丙二腈和水合肼串联四组分缩合反应

摘要 硼酸水溶液作为一种高效、绿色的催化体系，可以有效地利用芳醛与乙酰乙酸乙酯、丙二腈和水合肼的串联四组分缩合反应，得到吡喃并吡唑衍生物。通过硼酸与水反应制备H+，并在温和、绿色的条件下有效催化反应。