We report here the first rational synthesis of 5,10-diazaporphyrins via nucleophilic substitution reactions of α,α′-dibromotripyrrin. Uses of 1,3-diiminoisoindoline and 3,4-di(ethylsulfanyl)pyrrole-2,5-diimine as nucleophiles allowed for synthesis of 5,10-diazabenzoporphyrin (2) and 5,10-diaza-7,8-di(ethylsulfanyl)porphyrin (3). 3 was reduced to 5,10-diazaporphyrin (4), 5,10-diaza-2,3-dihydrogenated porphyrin (5), and 5,10-diaza-7,8-dihydrogenated porphyrin (6) with yields that were dependent upon reduction conditions. All the structures of these products were confirmed by X-ray crystallographic analysis. Their optical and electrochemical properties have been comparatively studied with those of 5,15-diazaporphyrin (7) and 5,15-diazachlorin (8). Furthermore, NH tautomers of 2 and 4 were observed as different species in solution, and the dynamic NH tautomeric behavior was studied in 4.
Bibliographical noteFunding Information:
This work was supported by JSPS KAKENHI grant numbers (JP18K14199, JP16H00909, and JP18H03910). M.U. acknowledges a JSPS Fellowship for Young Scientists. T.T. thanks financial supports from Murata Science Foundation and Izumi Science and Technology Foundation. The work at Yonsei University was supported by Strategic Research (NRF2016R1E1A1A01943379) through the National Research Foundation of Korea (NRF) funded by the Ministry of Science.
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All Science Journal Classification (ASJC) codes
- Organic Chemistry