dearomative cycloaddition of 3‐nitroindoles and 2‐nitrobenzofurans have emerged as a powerful protocol to construct chiral fused heterocyclic rings. However, organocatalytic dearomative reaction of these two classes of heteroarenes has become a long‐standing challenging task. Herein, we report the first example of phosphine‐catalyzed asymmetric dearomative [3+2]‐cycloadditio of 3‐nitroindoles and 2‐nitrobenzofurans
An efficient Ph2PMe-catalyzed dearomative (3 + 2) annulation of 2-nitrobenzofurans, 2-nitrobenzothiophenes, and 3-nitrobenzothiophenes with allenoates has been developed. With the developed protocol, a series of structurally important cyclopenta[b]benzofurans and cyclopenta[b]benzothiophenes were obtained in good to excellent yields (up to 98%) under mild conditions. In addition, preparative-scale
Palladium-Catalyzed Highly Stereoselective Dearomative [3 + 2] Cycloaddition of Nitrobenzofurans
作者:Qiang Cheng、Hui-Jun Zhang、Wen-Jun Yue、Shu-Li You
DOI:10.1016/j.chempr.2017.06.015
日期:2017.9
we report a highly stereoselective construction of tetrahydrofurobenzofurans and tetrahydrofurobenzothiophenes via palladium-catalyzed dearomative [3 + 2] cycloaddition of nitrobenzofurans and nitrobenzothiophenes, respectively. Good to excellent yields (63%–92%), diastereoselectivity (13/1 → >20/1 dr), and enantioselectivity (75%–95% ee) were obtained, leading to products with vicinal stereogenic
An efficient enantioselective dearomatization of 2-nitrobenzofurans was realized by organocatalyzed one-step Michael addition to access structurally diverse 3,3′-disubstituted oxindoles.
An organocatalyzed asymmetric dearomative [3+2] annulation reaction of electron-deficient 2-nitrobenzo heteroarenes including 2-nitrobenzofurans, 2-nitrobenzothiophenes and 2-nitroindoles with 3-isothiocyanatooxindoles was developed. With a multiple hydrogen-bonding bifunctional thiourea as the catalyst, the reaction displays broad substrate scope and provides an access to structurally diverse polycyclic