Novel C‐acylated triazole derivatives of ravuconazole,an azole antifungal agent

Novel C‐acylated triazoles were synthesized from ravuconazole via bicyclic triazole lactone. The synthesis and antifungal activity of these C‐acylated derivatives are described.     

On the use of the modified Julia olefination for bryostatin synthesis

Modified Julia olefination reactions using aldehyde 27 and the benzothiazol-2-yl sulfones 13 and 39 provide efficient syntheses of alkenes 28 and 42, which are advanced intermediates for syntheses of bryostatins.     

A simple and economical method for the production of 13C,18O-labeled Fmoc-amino acids with high levels of enrichment: applications to isotope-edited IR studies of proteins

Isotope-edited IR of proteins has generated considerable interest. Double labeling with 13C and 18O with high levels of isotopic enrichment is required for residue-specific resolution. Current methods for the preparation of doubly labeled amino acids give modest 18O enrichment, limiting the utility of the approach. We report a simple and economical method for preparing 13C,18O-doubly labeled N-(9-fluorenylmethoxycarbonyl)amino acids with high levels of enrichment for residues that do not require acid-labile side-chain protecting groups.     

Duplex stability of DNA.DNA and DNA.RNA duplexes containing 3'-S-phosphorothiolate linkages

3'-S-Phosphorothiolate (3'-SP) linkages have been incorporated into the DNA strand of both a DNA.RNA duplex and a DNA.DNA duplex. Thermal melting (T(m)) studies established that this modification significantly stabilises the DNA.RNA duplex with an average increase in T(m) of about 1.4 degrees C per modification. For two or three modifications, the increase in T(m) was larger for an alternating, as compared to the contiguous, arrangement. For more than three modifications their arrangement had no effect on T(m). In contrast to the DNA.RNA duplex, the 3'-S-phosphorothiolate linkage destabilised the DNA.DNA duplex, irrespective of the arrangement of the 3'-SP linkages. The effect of ionic strength on duplex stability was similar for both the phosphorothiolate-substituted and the unmodified RNA.DNA duplexes. The results are discussed in terms of the influence that the sulfur atom has on the conformation of the furanose ring and comparisons are also drawn between the current study and those previously conducted with other modifications that have a similar conformational effect.     

Analysis of variation in the ovine ultra‐high sulphur keratin‐associated protein KAP5‐4 gene using PCR‐SSCP technique

Keratin‐associated proteins (KAPs) are one of the main structural components of the wool fibre. Variation in the KAP genes (KRTAPs) may affect the structure of KAPs and hence wool characteristics. In this study, we used PCR‐SSCP to analyse ovine KRTAP5‐4, a gene encoding a member of the KAP5 family. Five different PCR‐SSCP patterns were detected in the 250 sheep that were analysed. Either one or a combination of two patterns was observed for each sheep, which was consistent with these sheep being either homozygous or heterozygous at this locus. DNA sequencing revealed that these patterns represent five different DNA sequences. One of the sequences was identical to a published ovine KRTAP5‐4 sequence. The remaining four were unique, but shared a high homology with the published ovine KRTAP5‐4 sequence, suggesting that these sequences represent allelic variants of KRTAP5‐4. There were a total of six SNPs and one length polymorphism in the sequences. Of the five SNPs found in the coding region, four were non‐synonymous SNPs and would result in amino acid changes. The length polymorphism would affect the cysteine content of the putative peptide and this along with the SNPs may have an impact on the structure of KAP5‐4, and hence affect wool traits.     

Field-based ion generation from microscale emitters on natural and artificial objects for atmospheric pressure mass spectrometry

Field-based ion generation is described for ambient mass spectrometry. The technique allows the analysis of endogenously expressed chemicals and exogenously applied compounds directly from the cuticle of live insects in real time. Cuticular hairs serve as electric field-enhancing structures and play a key role in ion generation. Artificial emitters such as graphite whiskers or sharp metal tips replicate this effect.     

Organocatalytic asymmetric cross-aldol reaction of 2-chloroethoxy acetaldehyde: diversity-oriented synthesis of chiral substituted 1,4-dioxanes and morpholines

Herein we report a facile organocatalytic asymmetric direct cross-aldol reaction of 2-chloroethoxy acetaldehyde with aromatic aldehydes using (S)-(?)-α,α-diphenyl-2-pyrrolidinemethanol as an organocatalyst to afford anti-2-(2-chloroethoxy)-1-arylpropane-1,3-diols with excellent enantioselectivities (95–98%) and moderate diastereoselectivities (3.5–7:1). The 1,3-diols, obtained after the aldehyde reduction, represent highly functional intermediates that allow for further diversification into both chiral 1,4-dioxanes and morpholines, compounds that frequently display interesting biological activities.     

Root subsystems of loop extensions

We completely classify the real root subsystems of root systems of loop algebras of Kac–Moody Lie algebras. This classification involves new notions of “admissible subgroups” of the coweight lattice of a root system Ψ, and “scaling functions” on Ψ. Our results generalise and simplify earlier work on subsystems of real affine root systems.