Double Ring Expansion from an Aromatic [18]Porphyrin(1.1.1.1) to an Antiaromatic [20]Porphyrin(2.1.2.1) |
| |
| Authors: | Masataka Umetani Dr Takayuki Tanaka Taeyeon Kim Prof Dr Dongho Kim Prof Dr Atsuhiro Osuka |
| |
| Institution: | 1. Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto, Japan;2. Spectroscopy Laboratory for Functional π-Electronic Systems and Department of Chemistry, Yonsei University, Seoul, Korea |
| |
| Abstract: | Double ring expansion from a 5,15‐diarylporphyrin to a 5,16‐diaryl‐10,11,21,22‐tetradehydro20]porphyrin(2.1.2.1) occurred through a reaction sequence consisting of oxidation with PbO2 to 5,15‐dioxoporphodimethene, a Corey–Fuchs reaction with tetrabromomethane in the presence of triphenylphosphine, and Fritsch–Buttenberg–Wiechell rearrangement triggered by tert‐butyllithium. The obtained tetradehydro20]porphyrin(2.1.2.1) and its mono‐ and dihydrogenated congeners exhibited 20 π antiaromatic character, whereas overhydrogenated congeners bearing a saturated bridge were nonaromatic owing to disrupted π conjugation. |
| |
| Keywords: | antiaromaticity expanded porphyrins porphyrins rearrangement vinylogous porphyrins |
|
|
