Hinkle Robert J, Chen Yuzhou, Nofi Colleen P, Lewis Shane E
Department of Chemistry, The College of William & Mary, P.O. Box 8795, Williamsburg, Virginia 23187-8795, USA.
Org Biomol Chem. 2017 Sep 20;15(36):7584-7593. doi: 10.1039/c7ob01412k.
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 BF·OEt 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.
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被用于构建三环1,4-二氢-2H-苯并[f]异色烯。该串联反应由BF·OEt引发，涉及炔基-普林斯环化、傅克烯基化以及脱水/芳构化，以形成一个新的中心芳环并消除2当量的水。1-芳基-3-己炔-2,6-二醇芳环上的供电子取代基以及富电子的醛反应伙伴均能显著提高总产率。对于2,4-二取代的2H-苯并[f]异色烯产物，炔基-普林斯反应中的非对映选择性约为1.4∶1，有利于顺式非对映异构体。通过X射线晶体学分析验证了一种顺式产物的立体化学结构，并且通过X射线分析也验证了另一种结构。
