Apurinic DNA reactivity: Modelisation of apurinic DNA breakage with phenylhydrazine and formation of a pyrazole adduct

We have elucidated the exact mechanism of apurinic oligodeoxynucleotide d(Tp[AP]pT) cleavage by phenylhydrazine and shown that the final isolated product is in fact a 3-substituted derivative of 1-phenyl-pyrazole.     

Structure of absintholide a new guaianolide dimer of Artemisia absinthium L.

Absintholide $\text{1}$ is a new guaianolide dimer whose structure and stereochemistry has been elucidated on the basis of high resolution n.m.r.     

Synthesis of new allenic prostanoids

New allenic prostanoids 5c, d, 7,9c, and 15b have been prepared by total synthesis. In each case a cuprate-propargylic acetate reaction was used as the key step.     

Improved procedure for the preparation of deoxynucleoside phosphoramidites: Arylphosphoramidites as new convenient intermediates for oligodeoxynucleotide synthesis

A simplified procedure for the preparation of deoxynucleoside methyl- and arylphosphoramidites is described. Both types of phosphoramidites can be conveniently activated by N-methylaniline trifluoracetate for their use in oligodeoxynucleotide synthesis.     

Growth ofschizosaccharomyces pombe on glucose-malte mixtures in continuous cell-recycle cultures kinetics of substrate utilization

The aerobic growth ofSchizosaccharomyces pombe on mixtures of glucose and malate was investigated during continuous high cell density cultures with partial cell-recycle using a membrane bioreactor. Determination of the specific metabolic rates relative to substrates and products allowed the capacity of the yeast to metabolize malic acid under both oxidative metabolism (carbon limited cultures) and oxidofermentative metabolism (carbon sufficient cultures) situations to be characterized. Under carbon limiting conditions, the specific rate of malate utilization was dependent on the residual concentration and a limit for a purely oxidative breakdown without ethanol formation was observed for a characteristic ratio between the rates of substrate consumption qm/qg of 1.63 g.g^-1. In addition, the mass balance analysis revealed the incorporation of malic acid into biomass. In carbon excess environments, the specific rate of malate utilization was dependent on both the residual malate and the specific rate of glucose consumption indicating that in addition to its conversion into ethanol malate can be respiratively metabolized for qm/qg ratios higher than 0.4 g.g^-1.     

Selenium-77 nuclear magnetic resonance in mono- and disubstituted benzo[b]selenophenes

The ⁷⁷Se chemical shifts of 79 mono- or disubstituted benzo[b]selenophenes are reported. The results in the 2- and 3-substituted derivatives closely parallel those previously obtained in the corresponding selenophenes. The measured parameters also correlate well with those measured in benzo[b]tellurophenes. The ¹²⁵Te and ⁷⁷Se chalcogen nuclei appear to be much more sensitive to substituent effects than the more classical nuclei. The effects of Cr(acac)₃, Eu(dpm)₃ and concentration on the ⁷⁷Se NMR spectra are briefly discussed.     

5,6-dihydropyridine: synthesis and characterization

5,6-dihydropyridine 1 is synthesized either by flash vacuum thermolysis of 1-azabicyclo[2.2.2] oct-2-ene 3 or by dehydrochlorination over solid bases of N-chloro-1,2,5,6-tetrahydropyridine 4 and characterized at low temperature by its ¹H and ¹³C nmr and ir spectra.