Aqueous microwave-assisted cross-coupling reactions applied to unprotected nucleosides.

Metal catalyzed cross-coupling reactions have been the preferred tools to access to modified nucleosides (on the C5-position of pyrimidines and on the C7- or C8-positions of purines). Our objective is to focus this mini-review on the Suzuki-Miyaura and on the Heck cross-couplings of nucleosides using microwave irradiations which is an alternative technology compatible with green chemistry and sustainable development.

High-affinity RNA targeting by oligonucleotides displaying aromatic stacking and amino groups in the major groove. Comparison of triazoles and phenyl substituents.

Three 5-modified 2'-deoxyuridine nucleosides were synthesized and incorporated into oligonucleotides and compared with the previously published 5-(1-phenyl-1,2,3-triazol-4-yl)-2'-deoxyuridine monomer W. The introduction of an aminomethyl group on the phenyl group led to monomer X, which was found to thermally stabilize a 9-mer DNA:RNA duplex, presumably through the partial neutralization of the negative charge of the backbone. By also taking advantage of the stacking interactions in the major groove of two or more of the monomer X, an extremely high thermal stability was obtained. A regioisomer of the phenyltriazole substituent, that is the 5-(4-phenyl-1,2,3-triazol-1-yl)-2'-deoxyuridine monomer Y, was found to destabilize the DNA:RNA duplex significantly, but stacking in the major groove compensated for this when two to four monomers were incorporated consecutively. Finally, the 5-phenyl-2'-deoxyuridine monomer Z was incorporated for comparison, and it was found to give a more neutral influence on duplex stability indicating less efficient stacking interactions. The duplexes were investigated by CD spectroscopy and MD simulations.

Antimycobacterial calixarenes enhance innate defense mechanisms in murine macrophages and induce control of Mycobacterium tuberculosis infection in mice.

Tuberculosis remains the leading cause of death among infectious diseases, accounting for more than two million deaths annually. The incidence of the disease is increasing globally, partially because of the resurgence of drug-resistant strains of Mycobacterium tuberculosis. Calixarenes are macrocyclic oligomers, some of which are able to modify the growth of M. tuberculosis in infected cells. Most experimental work has been carried out with Macrocyclon, also known as HOC 12.5EO. In this study, we demonstrate that Macrocyclon is effective in controlling M. tuberculosis infections, and we provide evidence that its effect is partially mediated by an l-arginine-dependent mechanism of macrophage activation that involves the activity of the inducible nitric oxide synthase. We also show that Macrocyclon is effective in athymic and major histocompatibility complex class II-/- mice and synthesized a number of structurally related calixarenes expressing significant antimycobacterial activity.

PtCl 2-catalyzed cycloisomerizations of allenynes.

The PtCl2-catalyzed cycloisomerization of allenyne systems has been examined. This process is a highly versatile tool for obtaining products that cannot be attainable with other metals. Simple adjustment of the allene or alkyne substitution can direct the reactivity in a selective manner and give birth to important carbocyclic frameworks (hydrindenes, cyclic vinylallenes, and trienes).

The selective functionalisation and difunctionalisation of p-substituted calix[6]arene and calix[8]arenes using hydrophilic moieties.

Methodologies to access water soluble large ringed calixarenes in good yield using efficient synthetic procedures have been investigated. Symmetrical partial functionalisations at the lower rim are described using activated [n]ethylene glycol chains and the addition behaviour contrasted with that of bromoalkanenitriles which proceeds with no observed regioselectivity. Full functionalisations of the calixarenes bearing hydrophilic groups are then investigated and a two-step procedure established which appears to be generally applicable for the addition of different [n]ethylene glycol chains. Furthermore, difunctionalisation under different reaction conditions are described. Throughout, strategies for the characterisation of these high mass compounds are outlined.