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Báez-Grez R, Pino-Rios R. On the aromaticity and stability of benzynes in the ground and lowest-lying triplet excited states. J Comput Chem 2024; 45:6-12. [PMID: 37671655 DOI: 10.1002/jcc.27214] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 08/02/2023] [Accepted: 08/09/2023] [Indexed: 09/07/2023]
Abstract
In this work, we have revisited the aromaticity of benzyne isomers at the unrestricted density functional theory level (UDFT) using the energetic, magnetic, and delocalization criteria. In addition, this last criterion has also been analyzed employing complete active space (CASSCF) calculations. The results show conservation of aromaticity in these monocycles. Additionally it is observed that this trend is maintained in polycyclic aromatic hydrocarbon derivatives such as biradical didehydrophenanthrenes. Do these results imply a violation of Baird's rule? The answer is No, because this conservation in aromaticity is due to the loss of hydrogen atoms affects only the electronic σ skeleton and exerts a minor influence on the π cloud. Additionally, we have analyzed the relative stability of benzyne isomers and their relationship with experimental ΔES-T values. According to the literature, the stability of the benzynes in the singlet state is due to an effective interaction between the electrons of the biradical centers; however, this effect is completely reversed in the triplet state, which explains why the para isomer has the lowest ΔES-T gap.
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Affiliation(s)
- Rodrigo Báez-Grez
- Departamento de Química, Facultad de Ciencias Exactas, Universidad Andres Bello, Santiago, Chile
| | - Ricardo Pino-Rios
- Instituto de Estudios de la Salud, Universidad Arturo, Chile
- Química y Farmacia, Facultad de Ciencias de la Salud, Universidad Arturo Prat, Chile
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Asahara H, Bonkohara A, Takagi M, Iwai K, Ito A, Yoshioka K, Tani S, Umezu K, Nishiwaki N. Development of a synthetic equivalent of α,α-dicationic acetic acid leading to unnatural amino acid derivatives via tetrafunctionalized methanes. Org Biomol Chem 2022; 20:2282-2292. [PMID: 35234775 DOI: 10.1039/d1ob02482e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Diethyl mesoxalate (DEMO) exhibits high electrophilicity and accepts the nucleophilic addition of a less nucleophilic acid amide to afford N,O-hemiacetal. However, our research showed that elimination of the amide moiety proceeded more easily than dehydration upon treatment with a base. This problem was overcome by reacting DEMO with an acid amide in the presence of acetic anhydride to efficiently obtain N,O-acetal. Acetic acid was eliminated leading to the formation of N-acylimine in situ upon treatment with the base. N-Acylimine is also electrophilic, accepting the second nucleophilic addition by pyrrole or indole to form α,α-disubstituted malonates. Subsequent hydrolysis followed by decarboxylation resulted in (α-indolyl-α-acylamino)acetic acid formation; homologs of tryptophan. Through this process, DEMO serves as a synthetic equivalent of α,α-dicationic acetic acid to facilitate nucleophilic introduction of the two substituents.
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Affiliation(s)
- Haruyasu Asahara
- School of Environmental Science and Engineering, Kochi University of Technology, Tosayamada, Kami, Kochi 782-8502, Japan. .,Graduate School of Pharmaceutical Sciences, Osaka University, Yamadaoka 1-6, Suita, Osaka 565-0871, Japan
| | - Atsushi Bonkohara
- School of Environmental Science and Engineering, Kochi University of Technology, Tosayamada, Kami, Kochi 782-8502, Japan.
| | - Masaya Takagi
- School of Environmental Science and Engineering, Kochi University of Technology, Tosayamada, Kami, Kochi 782-8502, Japan.
| | - Kento Iwai
- School of Environmental Science and Engineering, Kochi University of Technology, Tosayamada, Kami, Kochi 782-8502, Japan. .,Research Center for Molecular Design, Kochi University of Technology, Tosayamada, Kami, Kochi 782-8502, Japan
| | - Akitaka Ito
- School of Environmental Science and Engineering, Kochi University of Technology, Tosayamada, Kami, Kochi 782-8502, Japan. .,Research Center for Molecular Design, Kochi University of Technology, Tosayamada, Kami, Kochi 782-8502, Japan
| | - Kotaro Yoshioka
- Kumiai Chemical Industry Co. Ltd., Nakanogo, Fuji, Shizuoka 421-3306, Japan
| | - Shinki Tani
- Kumiai Chemical Industry Co. Ltd., Nakanogo, Fuji, Shizuoka 421-3306, Japan
| | - Kazuto Umezu
- Kumiai Chemical Industry Co. Ltd., Nakanogo, Fuji, Shizuoka 421-3306, Japan
| | - Nagatoshi Nishiwaki
- School of Environmental Science and Engineering, Kochi University of Technology, Tosayamada, Kami, Kochi 782-8502, Japan. .,Research Center for Molecular Design, Kochi University of Technology, Tosayamada, Kami, Kochi 782-8502, Japan
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Hwu JR, Panja A, Gupta NK, Huang W, Hu Y, Lin C, Hwang K, Chan W, Tsay S. Asymmetric Synthesis of 3‐Pyrrolines through an Aryne‐Induced Domino Process. ASIAN J ORG CHEM 2021. [DOI: 10.1002/ajoc.202000711] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Jih Ru Hwu
- Department of Chemistry and Frontier Research Center on Fundamental and Applied Sciences of Matters National Tsing Hua University Hsinchu 30013 Taiwan
| | - Avijit Panja
- Department of Chemistry and Frontier Research Center on Fundamental and Applied Sciences of Matters National Tsing Hua University Hsinchu 30013 Taiwan
| | - Nitesh K. Gupta
- Department of Chemistry and Frontier Research Center on Fundamental and Applied Sciences of Matters National Tsing Hua University Hsinchu 30013 Taiwan
| | - Wen‐Chieh Huang
- Department of Chemistry and Frontier Research Center on Fundamental and Applied Sciences of Matters National Tsing Hua University Hsinchu 30013 Taiwan
| | - Yu‐Chen Hu
- Department of Chemical Engineering National Tsing Hua University Hsinchu 30013 Taiwan
| | - Chun‐Cheng Lin
- Department of Chemistry and Frontier Research Center on Fundamental and Applied Sciences of Matters National Tsing Hua University Hsinchu 30013 Taiwan
| | - Kuo‐Chu Hwang
- Department of Chemistry and Frontier Research Center on Fundamental and Applied Sciences of Matters National Tsing Hua University Hsinchu 30013 Taiwan
| | - Wei‐Jen Chan
- Department of Chemistry and Frontier Research Center on Fundamental and Applied Sciences of Matters National Tsing Hua University Hsinchu 30013 Taiwan
| | - Shwu‐Chen Tsay
- Department of Chemistry and Frontier Research Center on Fundamental and Applied Sciences of Matters National Tsing Hua University Hsinchu 30013 Taiwan
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Zhu G, Lai X, Wang S, Lin C, Yuan Y. Synthesis of 2-Imino-1,2-dihydroquinolines via Copper Catalysis. CHINESE J ORG CHEM 2021. [DOI: 10.6023/cjoc202102037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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