Synthesis of Carbazole‐Containing Porphyrinoids by a Multiple Annulation Strategy: A Core‐Modified and π‐Expanded Porphyrin

Going around in circles: The copper(I)-mediated annulation of a doubly 1,3-butadiyne-bridged carbazole dimer with amines or Na2S provides isophlorins containing carbazole or thiophene-carbazole moieties, respectively (see scheme). Oxidization of the thiophene-containing isophlorin with MnO2 gives the corresponding porphyrin, which displays distinct aromaticity and remarkably intensified and red-shifted absorption bands in the near IR region.