Synthesis of 2′-C-methyl-branched isonucleosides

Novel regioisomers of 2′-methyl-branched nucleosides were designed and synthesized to mimic potent anti-viral drugs like Valopicitabine. The short and efficient synthesis of the targets involves a one-pot tosylation/cyclization step that leads to an activated furan scaffold on which the isonucleosides were built.     

Ueber das gleichzeitige Vorkommen eines l?slichen Bleisalzes und freier Schwefels?ure im Sherry-Wein

Ohne Zusammenfassung     

Ueber ein Verfahren Bleiglanz und andere Bleiverbindungen auf nassem Wege in kurzer Zeit auf Blei zu probiren

Ohne Zusammenfassung     

Chlorsaures Kali und Salpeters?ure als Oxydationsmittel

Ohne Zusammenfassung     

The enantioselective synthesis of (R)- and (S)-3-amino-3,4-dihydro-1H-[1,8]naphthyridin-2-one

A number of approaches to the enantioselective synthesis of (R)- and (S)-3-amino-3,4-dihydro-1H-[1,8]naphthyridin-2-one were studied. A novel one-pot asymmetric reduction/lactamization provided the desired products in high yield and enantiomeric excess.     

Esterification kinetics and mechanism of stereoisomers of substituted 4-hydroxypiperidines and cyclohexanols

Esterification rates of stereoisomeric substituted 4-hydroxypiperidines and cyclohexanols (in the presence of N-methylpiperidine) with benzoyl chloride in tetrachloroethylene at 25° are found to indicate intramolecular catalysis and intermolecular acylation, respectively. Isomers of 4-hydroxyperidines with an axial hydroxyl group undergo acylation four times as fast as their 4-equatorial hydroxyl epimers accounted for by higher stability of the resulting intermediate complex.     

Colloidal Surface Active Maghemite Nanoparticles for Biologically Safe CrVI Remediation: from Core‐Shell Nanostructures to Pilot Plant Development

The present study is aimed at the exploration of achievable improvements for Cr^VI ex situ and in situ water remediation by using novel naked colloidal maghemite (γ‐Fe₂O₃) nanoparticles (surface active maghemite nanoparticles, SAMNs). The reliability of SAMNs for Cr^VI binding and removal was demonstrated, and SAMN@Cr^VI complex was characterized, as well as the covalent nature of the absorption was unequivocally proved. SAMNs were structurally and magnetically well conserved after Cr^VI binding. Thus, in consideration of their affinity for Cr^VI, SAMNs were exploited in a biological model system, mimicking a real in situ application. The assay evidenced a progressive reduction of revertant colonies of Salmonella typhimurium TA100 strain, as maghemite nanoparticles concentration increased, till the complete suppression of Cr^VI mutagen effect. Finally, an automatic modular pilot system for continuous magnetic removal and recovery of Cr^VI from water is proposed. SAMNs, thanks to their colloidal, binding, and catalytic properties, represent a promising tool as a reliable nanomaterial for water remediation by Cr^VI.     

Substitution‐Inert Polynuclear Platinum Complexes That Inhibit the Activity of DNA Polymerase in Triplex‐Forming Templates

The formation of triple‐helical DNA is implicated in the regulation of gene expression. The triplexes are, however, unstable under physiological conditions so that effective stabilizers for the triplex formation are needed. Herein, we describe a new strategy for the stabilization of such triplexes that is based on antitumor substitution‐inert polynuclear platinum complexes (SI‐PPCs). These compounds were previously shown to bind to DNA through the phosphate clamp—a discrete mode of DNA–ligand recognition distinct from the canonical intercalation and minor‐groove binding. We have found that SI‐PPCs efficiently inhibit DNA synthesis by DNA polymerase in sequences prone to the formation of pyrimidine‐ and purine‐motif triplex DNAs. Moreover, the results suggest that SI‐PPCs are able to induce the formation of triple‐helical DNA between duplexes and strands that are not completely complementary to each other. Collectively, these data provide evidence that SI‐PPCs are very efficient stabilizers of triple‐stranded DNA that might exert their action by stabilizing higher‐order structures such as triple‐helical DNA.     

Local polarity in CO2-expanded acetonitrile: a nucleophilic substitution reaction and solvatochromic probes

Many processes that use highly tunable gas-expanded liquids (GXLs) rely on the fact that CO2 addition can greatly affect the polarity of the solvent. We have examined several measures of bulk and local polarity in CO2-expanded acetonitrile to enable more effective exploitation of these polarity changes. The rate of the nucleophilic substitution reaction of tributylamine with methyl p-nitrobenzenesulfonate has been analyzed as a function of solvent composition by using in situ high-pressure UV/vis spectroscopy. We have also measured solvatochromic properties including the Kamlet-Taft pi* parameter and Kosower's Z-value. We correlate these local polarity-based kinetic and solvatochromic measures to develop a better understanding of these property changes as a function of bulk and local solvent composition. The data suggest that local composition enhancement in CO2-expanded acetonitrile has a significant impact on the reaction kinetics.