Organocatalytic Enantioselective [8+4] Cycloadditions of Isobenzofulvenes for the Construction of Bicyclo[4.2.1]nonanes

Main observation and conclusion The [8+4] cycloaddition of indene-2-carbaldehydes with indole-2,3-quinodimethanes and pyrrolidone-3,4-dienes is described, affording indole and pyrrolidone annulated bicyclo[4.2.1]nonanes in a highly peri-, diastereo-, and enantioselective fashion in the presence of a secondary amine catalyst. This reaction, which proceeds through catalytically generated isobenzofulvenes, represents the first asymmetric version of high-order [8+4] cycloaddition.