3 research outputs found
The role of germinal vesicle in maturation of Pleurodeles waltlii oocytes induced by steroids
Lanthanide-Catalyzed Oxyfunctionalization of 1,3-Diketones, Acetoacetic Esters, And Malonates by Oxidative C–O Coupling with Malonyl Peroxides
The lanthanide-catalyzed oxidative
C–O coupling of 1,3-dicarbonyl
compounds with diacyl peroxides, specifically the cyclic malonyl peroxides,
has been developed. An important feature of this new reaction concerns
the advantageous role of the peroxide acting both as oxidant and reagent
for C–O coupling. It is shown that lanthanide salts may be
used in combination with peroxides for selective oxidative transformations.
The vast range of lanthanide salts (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb,
Dy, Ho, Er, Y) catalyzes oxidative C–O coupling much more efficiently
than other used Lewis and Bronsted acids. This oxidative cross-coupling
protocol furnishes mono and double C–O coupling products chemo-selectively
in high yields with a broad substrate scope. The double C–O
coupling products may be hydrolyzed to vicinal tricarbonyl compounds,
which are otherwise cumbersome to prepare. Based on the present experimental
results, a nucleophilic substitution mechanism is proposed for the
C–O coupling process in which the lanthanide metal ion serves
as Lewis acid to activate the enol of the 1,3-dicarbonyl substrate.
The side reactions–chlorination and hydroxylation of the 1,3-dicarbonyl
partners–may be minimized under proper conditions