Reactions of Antiaromatic Norcorrole Ni(II) Complex with Carbenes

Org Lett. 2020 Jun 5;22(11):4400-4403. doi: 10.1021/acs.orglett.0c01402. Epub 2020 May 11.

Abstract

Norcorrole is a ring-contracted porphyrinoid, exhibiting distinct antiaromaticity. Herein, we report the reactions of meso-dimesitylnorcorrole Ni(II) complex with two types of carbenes: dichlorocarbene and an N-heterocyclic carbene (NHC). The reaction with in-situ-generated dichlorocarbene resulted in the double insertion of two chloromethine units to provide a mixture of 5,15-dichloroporphyrin and chlorinated isopyricorroles. The nucleophilic NHC attacked the 3-position of the norcorrole core and the subsequent proton transfer furnished a nonconjugated macrocycle incorporating a diazafulvene segment.