Two-Step, Practical, and Diversity-Oriented Synthesis of Multisubstituted Benzofurans from Phenols through Pummerer Annulation Followed by Cross-coupling
作者:Kei Murakami、Hideki Yorimitsu、Atsuhiro Osuka
DOI:10.1246/bcsj.20140241
日期:2014.12.15
Practical and diversity-oriented synthesis of multisubstituted benzofurans has been accomplished from simple phenols through a Pummerer annulation/cross-coupling sequence. Operationally simple and rapid reactions of phenols with ketene dithioacetal monoxides (KDMs) with the aid of trifluoroacetic anhydride provide the corresponding 2-methylsulfanylbenzo[b]furans. The scope of the reaction encompasses phenols and KDMs having a broad range of substituents. The remaining methylsulfanyl group in the annulation products is converted to various aryl groups through cross-coupling reactions that we improved specially to this end. This two-step approach to multisubstituted benzofurans is powerful enough to synthesize highly fluorescent benzofuran derivatives as well as the naturally occurring Eupomatenoid family.
Practical, Modular, and General Synthesis of Benzofurans through Extended Pummerer Annulation/Cross-Coupling Strategy
作者:Kei Murakami、Hideki Yorimitsu、Atsuhiro Osuka
DOI:10.1002/anie.201403288
日期:2014.7.14
Operationally simple, efficient, and widely applicable Pummerer annulations of simple phenols with ketene dithioacetal monoxides, with the aid of trifluoroacetic anhydride, have been shown to provide a variety of benzofurans having a methylthio group at the 2‐position. Subsequent and newly developed nickel‐catalyzed arylation at the methylthio group culminates in diversity‐oriented synthesis of multisubstituted