An unprecedented metal-free synthesis of 4-(methylthio)chromeno[4,3-c]pyrazol-3(2H)-one is reported via sequential one-pot desulfitative [5+1] hetero-annulation. The present strategy consists of one-pot sequential, base catalysed dithioketene formation from active methylene of pyrazolone followed by methylation and [5+1] heteroannulative cyclization. The resulting substrate undergoes facile nucleophilic substitution with various amines to yield 4-(substituted-amine)-chromeno[4,3-c]pyrazol-3(2H)-one derivatives under metal free condition.

中文翻译：

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chromeno [4,3 - c ] pyrazol-3（2 H）-one衍生物的无金属合成

通过连续的一锅式脱硫[5 + 1]杂化环空报道了空前的无金属合成4-（甲硫基）chromeno [4,3 - c ]吡唑-3（2H）-。本策略包括由吡唑啉酮的活性亚甲基一锅顺序地，碱催化的二硫代乙烯酮形成，然后进行甲基化和[5 + 1]杂环化环化。所得的底物用各种胺进行容易的亲核取代，以在无金属条件下产生4-（取代的胺）-铬[4,3 - c ]吡唑-3（2H）-一衍生物。