Synthesis of urea derivatives via reductive carbon dioxide fixation into contracted porphyrin analogues

Abstract

Carbon dioxide from ammonium carbonate is trapped by the free base corroles with the help of two adjacent inner NH groups (N²¹ and N²²) and forms the N²¹,N²²-carbamide-corrole derivatives. There is an extensive literature on functionalized ureas and their potent pharmaceutical applications. While the aliphatic, aromatic, alicyclic, and heterocyclic analogues of differently substituted ureas are well established, the N²¹,N²²-carbamide-porphyrinoid derivatives have been reported rarely. Herein we present a new synthetic protocol to synthesize N²¹,N²²-carbamide-corroles. These results thus open a greener avenue (without using any toxic chemicals like phosgene, CO, or isocyanate) for functionalized urea derivatives bearing porphyrinoid analogues.