Synthesis of Benzofuran-3(2H)-ones
A Hg(OTf)2-catalyzed N-oxide addition to alkynes forms an enolonium species, that can undergo intramolecular nucleophilic attack by hydroxyl or amino groups, providing various coumaran-3-ones and indolin-3-ones via an enolate umpolung reactivity.
Z. Rong, W. Hu, N. Dai, G. Qian, Org. Lett., 2020, 22, 3245-3250.
An asymmetric dual-metal relay catalysis strategy that combines Rh/chiral sulfur-olefin-catalyzed enantioselective 1,2-addition with a Pd-catalyzed intramolecular C-O coupling enables a rapid and efficient synthesis of quaternary carbon-containing gem-diaryl benzofuran-3(2H)-ones in good yields in a highly enantioselective manner.
Z.-F. Zhang, D.-X. Zhu, W.-W. Chen, B. Xu, M.-H. Xu, Org. Lett., 2017, 19, 2726-2729.
An N-Heterocyclic carbene efficiently catalyzed an intramolecular nucleophilic substitution reaction to yield benzopyrones and benzofuranones depending on the substitution pattern.
J. He, J. Zheng, J. Liu, X. She, X. Pan, Org. Lett., 2006, 8, 4637-4640.
A Rh/Co relay catalyzed C-H functionalization/annulation of N-aryloxyacetamides with propiolic acids provides valuable benzofuran-3(2H)-one scaffolds with a quaternary center in good yields.
W.-K. Yuan, M.-H. Zhu, R.-S. Geng, G.-Y. Ren, L.-B. Zhang, L.-R. Wen, M. Li, Org. Lett., 2019, 21, 1654-1658.