Exploring Coumarins Reduction: NaBH 4 /MeOH versus Nickel Boride Generated In Situ .
Résumé
The role of reagents NaBH4/MeOH and nickel boride (Ni2B)
generated in situ from NaBH4 and NiCl2, are compared in the
reduction process of coumarin and a variety of 3,7-substituted
coumarins bearing electro-donating (ED-group) or electro-withdrawing
groups (EW-group). Coumarins (chromen-2-ones) are
only reduced by Ni2B to the cyclic chromanones. This provides
a useful and very simple reduction method for electron-rich
coumarins, which are resistant to many other reducing
methods. DFT calculations underlined the role of substituents
electronic effects in the reactivity. Subsequent methanolysis
may open the ring to methyl phenylpropanoate esters and
alcohols resulting from their reductions can also be produced.
Domaines
Chimie organiqueOrigine | Fichiers produits par l'(les) auteur(s) |
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