Efficient ortho-formylation in vitamin E series, application to the semi-synthesis of natural 5- and 7-formyl-δ-tocotrienols revealing an unprecedented 5-bromo-7-formyl exchange - Université d'Angers Accéder directement au contenu
Article Dans Une Revue Tetrahedron Année : 2017

Efficient ortho-formylation in vitamin E series, application to the semi-synthesis of natural 5- and 7-formyl-δ-tocotrienols revealing an unprecedented 5-bromo-7-formyl exchange

Résumé

Semi-synthesis of 5- and 7-formyltocopherols and tocotrienols has been developed by ortho-formylation of C-5 or C-7-unsubstituted vitamin E derivatives (14 examples) up to 90% yield, through heating in the presence of respectively 10-10-15 equivalents of MgCl2-Et3N-(CH2O)n. Formylation of 5-bromo-δ-tocotrienol revealed an unprecedented 5-bromo/7-formyl exchange and yielded 7-bromo-5-formyl-δ-tocotrienol as major product. The minor 5-bromo-7-formyl-δ-tocotrienol led in three steps to 7-formyl-δ-tocotrienol previously isolated from the stem bark of Garcinia virgata.

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hal-02521270 , version 1 (27-03-2020)

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Khaled Alsabil, Guillaume Viault, Sorphon Suor-Cherer, Jean-Jacques Helesbeux, Joumaa Merza, et al.. Efficient ortho-formylation in vitamin E series, application to the semi-synthesis of natural 5- and 7-formyl-δ-tocotrienols revealing an unprecedented 5-bromo-7-formyl exchange. Tetrahedron, 2017, 73 (49), pp.6863-6870. ⟨10.1016/j.tet.2017.10.039⟩. ⟨hal-02521270⟩
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