Radical cations show a unique reactivity that is fundamentally different from that of conventional cations and have thus attracted considerable attention as alternative cationic intermediates for novel types of organic reactions. However, asymmetric catalysis to promote enantioselective radical cation reactions remains a major challenge in contemporary organic synthesis. Here, we report that the judicious design of an ion pair consisting of a radical cation and a chiral counteranion induces an excellent level of enantioselectivity. This strategy was applied to enantio-, diastereo-, and regioselective [2 + 2] cycloadditions, as well as enantio-, diastereo-, and regioselective [4 + 2] cycloadditions, by using chiral iron(III) photoredox catalysis. We anticipate that this strategy has the potential to expand the use of several mature chiral anions to develop numerous unprecedented enantioselective radical cation reactions.

We describe a practical method for synthesizing heterocycle-2,3-fused indoline or azaindoline derivatives through haloetherification and cyclization. We applied this method in syntheses of six- to eight-membered heterocycle-2,3-fused indoline and azaindoline derivatives. These derivatives, which contain sp3-hybridized carbons, might be useful as new scaffolds in medicinal chemistry.

Die Pyridone (II) reagieren mit dem Dimethylbutadien (I) zu den Cycloaddukten (III), von denen (IIIb) bei der Behandlung mit Lithiumdiethylamid zum Bicyclus (IVb) isomerisiert wird.

Bei der Photolyse von 2,3‐Diphenyl‐naphthochinonoxid (I) entsteht das.

Die mesoionischen Verbindungen (I) bilden mit den Cyclopropen‐Derivaten (II) die Verbindungen (III).