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Iwai K, Hikasa A, Yoshioka K, Tani S, Umezu K, Nishiwaki N. Synthesis of Bis(functionalized) Aminals via Successive Nucleophilic Amidation and Amination. J Org Chem 2023; 88:2207-2213. [PMID: 36745736 DOI: 10.1021/acs.joc.2c02647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The central carbonyl group of diethyl mesoxalate (DEMO) exhibits high electrophilicity that allows it to be attacked by versatile nucleophiles. Even a less nucleophilic acid amide serves as a nucleophile to produce N,O-acetal upon treatment with DEMO in the presence of acetic anhydride. When the obtained N,O-acetal was treated with a base, the elimination of acetic acid generated N-acylimine in situ. N-Acylimine is also highly electrophilic, allowing it to accept the second nucleophilic addition by an amine, resulting in α,α-bis(functionalized) aminals. This protocol facilitates the modification of the two different amino groups by altering nucleophiles, resulting in the production of tetra-functionalized methane derivatives on demand. The ring closure between the amide moiety and the amino group was achieved using the structural features to form a six-membered ring.
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Affiliation(s)
- Kento Iwai
- School of Engineering Science, Kochi University of Technology, Tosayamada, Kami 782-8502, Kochi, Japan.,Research Center for Molecular Design, Kochi University of Technology, Tosayamada, Kami 782-8502, Kochi, Japan
| | - Akari Hikasa
- School of Engineering Science, Kochi University of Technology, Tosayamada, Kami 782-8502, Kochi, Japan
| | - Kotaro Yoshioka
- Kumiai Chemical Industry Co. Ltd., Nakanogo, Fuji 421-3306, Shizuoka, Japan
| | - Shinki Tani
- Kumiai Chemical Industry Co. Ltd., Nakanogo, Fuji 421-3306, Shizuoka, Japan
| | - Kazuto Umezu
- Kumiai Chemical Industry Co. Ltd., Nakanogo, Fuji 421-3306, Shizuoka, Japan
| | - Nagatoshi Nishiwaki
- School of Engineering Science, Kochi University of Technology, Tosayamada, Kami 782-8502, Kochi, Japan.,Research Center for Molecular Design, Kochi University of Technology, Tosayamada, Kami 782-8502, Kochi, Japan
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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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