Isothiourea-Catalyzed Enantioselective α-Alkylation of Esters via 1,6-Conjugate Addition to <i>para</i>-Quinone Methides
The isothiourea-catalyzed enantioselective 1,6-conjugate addition of <i>para</i>-nitrophenyl esters to 2,6-disubstituted <i>para</i>-quinone methides is reported. <i>para</i>-Nitrophenoxide, generated in situ from initial <i>N</i>-acylation of the isot...
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| Autores principales: | , , , , , , , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
MDPI AG
2021
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/355f0306f6ad4c5f949bcd0c0470370b |
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| Sumario: | The isothiourea-catalyzed enantioselective 1,6-conjugate addition of <i>para</i>-nitrophenyl esters to 2,6-disubstituted <i>para</i>-quinone methides is reported. <i>para</i>-Nitrophenoxide, generated in situ from initial <i>N</i>-acylation of the isothiourea by the <i>para</i>-nitrophenyl ester, is proposed to facilitate catalyst turnover in this transformation. A range of <i>para</i>-nitrophenyl ester products can be isolated, or derivatized in situ by addition of benzylamine to give amides at up to 99% yield. Although low diastereocontrol is observed, the diastereoisomeric ester products are separable and formed with high enantiocontrol (up to 94:6 er). |
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