Synthesis and Trapping of the Elusive <i>Ortho</i>-Iminoquinone Methide Derived from α-Tocopheramine and Comparison to the Case of α-Tocopherol
Tocopheramines are a class of antioxidants which are distinguished from tocopherols (vitamin E) by the presence of an amino group instead of the phenolic hydroxyl group. α-Tocopheramine is intensively studied for biomedical applications but also as a stabilizer for synthetic and natural polymers, in...
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| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-08-01
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| Series: | Molecules |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1420-3049/30/15/3257 |
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| Summary: | Tocopheramines are a class of antioxidants which are distinguished from tocopherols (vitamin E) by the presence of an amino group instead of the phenolic hydroxyl group. α-Tocopheramine is intensively studied for biomedical applications but also as a stabilizer for synthetic and natural polymers, in particular for cellulose solutions and spinning dopes for cellulosic fibers. This study addresses a fundamental difference in the oxidation chemistry of α-tocopheramine and its tocopherol counterpart: while the formation of the ortho-quinone methide (o-QM) involving C-5a is one of the most fundamental reactions of α-tocopherol, the corresponding ortho-iminoquinone methide (o-IQM) derived from α-tocopheramine has been elusive so far. Synthesis of the transient intermediate succeeded initially via 5a-hydroxy-α-tocopheramine, and its occurrence was confirmed by dimerization to the corresponding spiro-dimer and by trapping with ethyl vinyl ether. Eventually, suitable oxidation conditions were found which allowed for the generation of the o-IQM directly from α-tocopheramine. The underlying oxidation chemistry of α-tocopherol and α-tocopheramine is concisely discussed. |
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| ISSN: | 1420-3049 |