A three-step domino reaction between 1-aryl-3-hexyne-2,6-diol derivatives and aldehydes is used to construct tricyclic 1,4-dihydro-2H-benzo[f]isochromenes. The cascade is initiated by BF₃·OEt₂ and involves alkynyl-Prins cyclization, Friedel–Crafts alkenylation, and dehydration/aromatization to create a new, central aromatic ring and eliminate 2 equiv. of water. Electron-donating substituents on the aryl ring of the 1-aryl-3-hexyne-2,6-diols significantly increase overall yields as do electron-rich aldehyde reaction partners. For 2,4-disubstituted 2H-benzo[f]isochromene products, diastereoselectivities in the alkynyl-Prins reaction are ∼1.4:1 in favor of the cis-diastereomer. The stereochemistry of one cis-product was verified by X-ray crystallographic analysis and a second structure was also verified by X-ray analysis.

中文翻译：

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一锅芳构化级联反应的电子效应，涉及炔基-Prins环化，Friedel-Crafts烷基化和脱水成三环苯并[ f ]异色酮

1-芳基-3-己炔-2，6-二醇衍生物与醛之间的三步多米诺反应用于构建三环1，4-二氢-2 H-苯并[ f ]异色酮。级联反应是由BF ₃ ·OEt ₂引发的，涉及炔基-Prins环化，Friedel-Crafts烯基化和脱水/芳构化，以形成一个新的中心芳环并消除2个当量。水。1-芳基-3-己炔-2，6-二醇芳基环上的供电子取代基与富电子醛反应伙伴一样，可显着提高总收率。对于2,4-二取代的2 H-苯并[ f ]异戊二烯产物，炔基-普林斯反应中的非对映选择性为〜1.4 ：1表示顺式-非对映异构体。X射线晶体学分析证实了一种顺式产物的立体化学，X射线分析也证实了第二种结构的立体化学。