Fig. 2.

Background and initial insights. a Original strategy for the enantioselective iminium ion trapping of radicals based on the combination of a carbazole amine catalyst 3 and an exogenous photoredox catalyst (PC). b X-ray crystal structure of the carbazole-based iminium ion A-1. c UV–Vis spectra of the carbazole catalyst 3b (structure in Table 1) and iminium ions A-1 and A-2 [1.0 mM] in CH₃CN