1
|
Nakata M, Hirashita T, Konishi Y, Araki S. Synthesis of stable class 5 mesoionic benzo[ c]tetrazolo[2,3- a]cinnolinium thiolate, dicyanomethylide, and amides. Org Biomol Chem 2023; 21:4282-4289. [PMID: 37158001 DOI: 10.1039/d3ob00362k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Although class 5 mesoionic compounds show interesting electrical behaviour, they are generally unstable, readily undergoing ring-opening reactions. We designed and synthesized a bridged mesoionic derivative, benzo[c]tetrazolo[2,3-a]cinolinium (BTC), as a stable class 5 mesoionic compound, which was further transformed to the corresponding thiolate, cicyanomethylide, and amide. The intramolecular bridging imparted stability to the BTC thiolates and amides: the BTC thiolates were unsusceptible to ring-opening at high temperatures, and the BTC amides were stable in the absence of electron-withdrawing groups on the amide nitrogen. The properties of the BTC thiolate were compared with those of 2,3-diphenyltetrazolium derivatives based on UV-Vis absorption spectroscopy, single-crystal X-ray diffraction and quantum calculations.
Collapse
Affiliation(s)
- Mirai Nakata
- Life Science and Applied Chemistry, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, Aichi, 466-8555, Japan.
| | - Tsunehisa Hirashita
- Life Science and Applied Chemistry, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, Aichi, 466-8555, Japan.
| | - Yoshikazu Konishi
- Life Science and Applied Chemistry, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, Aichi, 466-8555, Japan.
| | - Shuki Araki
- Life Science and Applied Chemistry, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, Aichi, 466-8555, Japan.
| |
Collapse
|
2
|
A theoretical study of the valence tautomerism of 1H-pyrazolium-4-olates (X = O) and related compounds (X = S, Se, NH): relative stabilities, protonation effects, and tautomerization barriers. Struct Chem 2022. [DOI: 10.1007/s11224-022-01962-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Abstract
The valence isomerism of a series of heterocyclic mesomeric betaines (HMBs) belonging to class 5, called pseudo-semi-conjugated HMBs, has been studied theoretically both the neutral and the protonated species. These HMBs are 1H-pyrazol-2-ium-4-olates and related compounds where the oxygen atom has been replaced by S, Se atoms, and an NH group. The main conclusion of the present work is that the ring/open valence tautomerism is possible both for neutral and protonated although it has never been observed experimentally.
Collapse
|