Tandem Construction of Indole-Fused Phthalazines from (2-Alkynylbenzylidene)hydrazines under Metal-Free Conditions

An efficient approach to invent diversely substituted indole-fused phthalazines from in situ formed (2-alkynylbenzylidene)­hydrazines under metal-free conditions via selective radical cyclization has been developed. Notably, this 6-exo-dig addition–cyclization tandem procedure proceeds under air atmosphere and shows a broad substrate suitability, as well as avoids harmful byproducts, which complies with the concept of green synthesis.本研究开发了一种高效方法，可通过选择性自由基环化过程，在无金属条件下，由原位生成的(2-炔基苯亚甲基)肼类化合物，构建多取代吲哚并酞嗪类衍生物。值得注意的是，该6-exo-dig加成-环化串联反应可在空气氛围下进行，底物适用范围广泛，且不会产生有害副产物，符合绿色合成理念。