ABSTRACT
Lipidic cubic phases (LCPs) can reduce Pd2+ salts to palladium nanoparticles (PdNPs) of â¼5 nm size in their confined water channels under mild conditions. The resulting PdNP-containing LCPs were used as nanoreactor scaffolds to catalyze Suzuki-Miyaura cross-coupling reactions in the aqueous channels of the mesophase. To turn on catalysis, PdNP-containing LCPs were activated by swelling the aqueous channels of the lipidic framework, thereby enabling diffusion of the water-soluble substrates to the catalysts. The mesophases play a threefold role: they act as reducing agents for Pd2+, as limiting templates for their growth, and as support. The system was characterized and investigated by small-angle X-ray scattering (SAXS), cryo-transmission electron microscopy, dynamic light scattering, and nuclear magnetic resonance. Bulk LCPs and three dispersed palladium/lipid hybrid nanoparticle types were applied in the catalysis. The latter-liposomes, hexosomes, and cubosomes-can be obtained by design through combination of lipids and additives. The Suzuki-Miyaura cross-coupling of 5-iodo-2'-deoxyuridine and phenylboronic acid was used as a model reaction to study these systems. Bulk Pd-LCPs deliver the Suzuki-Miyaura product in 24 h in conversions up to 98% at room temperature, whereas with palladium/lipid dispersions at 40 °C, 68% of the starting material was transformed to the product after 72 h.
ABSTRACT
A methodology for the synthesis of oligophosphate conjugates using phosphordiamidites is described. This strategy facilitates the straightforward preparation of C2-symmetric dinucleoside tri-, penta-, and heptaphosphates. Moreover, unsymmetric compounds such as thiamine adenosine triphosphate and thiamine cytidine triphosphate can be prepared. The material is used to study the inhibitory activity of thiaminylated nucleotides against adenosine diphosphate ribosyltransferases.
