Catalytic Asymmetric Dearomative [3 + 2] Cycloaddition of Electron-Deficient Indoles with All-Carbon 1,3-Dipoles

The first catalytic
asymmetric dearomative [3 + 2] cycloaddition
of 3-nitroindoles with vinylcyclopropanes has been established, which
constructed chiral cyclopenta­[b]­indoline scaffolds
in generally high enantioselectivities (up to 97% ee). This reaction
also represents the first application of all-carbon 1,3-dipoles in
catalytic asymmetric dearomative [3 + 2] cycloadditions of 3-nitroindoles.
This approach will not only advance the catalytic asymmetric dearomatization
reactions of electron-deficient indoles but also provide an efficient
method for constructing chiral cyclopenta­[b]­indoline
scaffolds.