Phosphine‐Catalyzed Enantioselective Dearomative [3 + 2]‐Cycloaddition of 3‐Nitroindoles and 2‐Nitrobenzofurans

Over past years, the metal‐catalyzed 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 reported the first example of phosphine‐catalyzed asymmetric dearomative 3‐nitroindoles and 2‐nitrobenzofurans was realized, which provide a new, facile, and efficient protocol for the synthesis of chiral 2,3‐fused cyclopentannulated indolines and dihydrobenzofurans by reacting with allenoates and MBH carbonates, respectively via dearomative [3 + 2]‐cycloaddition.

from A via a.sfakia on Inoreader http://bit.ly/2N2lavJ