Cu-mediated syntheses of N-fused and ring-modified trithiahexaphyrins.
The reaction of the antiaromatic [28]trithiahexaphyrin (TTHP) with Cu(I) in DMF gives a novel fused-ring trithiahexaphyrin with the elimination of a chloride on a dichlorophenyl ring and bond formation to the outward oriented pyrrolic nitrogen to form a 5,5,6-tricyclic internal ring system. The NMR spectra, which display characteristics of an antiaromatic compound, agree with the proposed structure. Meanwhile, reactions of TTHP with amines in the presence of Cu(I) give amino-group-inserted hexaphyrins with the amino nitrogen joined to a beta-thiophenic carbon and the alpha-carbon of the alkylamine cyclized to the inward pyrrolic nitrogen to form a 5,7,5-tricyclic rings. The crystal structure of the fused-ring product indicates a rectangular geometry with a tilted tricyclic ring system, while the ring-modified TTHP-DMA complex gives a triangular trithiahexaphyrin core. This report demonstrates methods to incorporate functionalized heterocyclic rings into expanded porphyrins.