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Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions
Published on: July 17, 2020
Phosphine-catalyzed [4 + 2] cyclization of para-quinone methide derivatives with allenes
Fu-Ru Yuan1, Fei Jiang, Ke-Wei Chen
1School of Chemistry and Materials Science, Jiangsu Normal University, Xuzhou, 221116, China. fshi@jsnu.edu.cn.
Abstract:
The first [4 + 2] cyclization of para-quinone methide (p-QM) derivatives with allenes has been established via phosphine catalysis, which afforded a series of chroman derivatives in high yields (up to 97%) and excellent (E/Z)-selectivities (all >95 : 5 E/Z). This reaction will not only enrich the research contents of cyclization reactions involving p-QM derivatives, but also provide a good example of the application of allenes and phosphine catalysis in cyclization reactions. In addition, this approach also offers a useful method for the construction of chroman scaffolds.
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