Nonlinear Multivariate SAR of Lepidoptera Pheromones

Abstract

The combined use of the nonlinear mapping method with correspondence factor analysis allowed to derive interesting structure-chemoreception relationships in Lepidoptera. A chemotaxonomy of insects based on their responses to pheromones was also proposed.     

Homology model of the rainbow trout estrogen receptor (rtERalpha) and docking of endocrine disrupting chemicals (EDCs)

A model for rainbow trout (Oncorhynchus mykiss) estrogen receptor (rtERa) was built by homology with the human estrogen receptor (hERa). A high level of sequence conservation between the two receptors was found with 64% and 80% of identity and similarity, respectively. Selected endocrine disrupting chemicals were docked into the ligand binding domain (LBD) of rtERa and the corresponding free binding energies Delta(DeltaG(bind)) values were calculated. A Quantitative Structure-Activity Relationship (QSAR) model between the relative binding affinity data and the Delta(DeltaG(bind)) values was derived in order to predict which further organic pollutants are likely to bind to rtERa.     

Relative Electrophilic Fluorinating Power as Assayed by Competitive Catalytic Halogenation Reactions

Catalytic fluorination/chlorination competition experiments of β‐keto ester 5 were used to assess the relative fluorinating activity of various electrophilic N? F reagents (containing an N? F bond). Thus, in the halogenation reactions catalyzed by the [Ti(TADDOLato)] complex 1 (=bis(acetonitrile)dichloro[(4R,5R)‐2,2‐dimethyl‐α,α,α′,α′‐tetra(naphthalen‐1‐yl)‐1,3‐dioxolane‐4,5‐dimethanolato(2?)‐κO,κO′]titanium), the activity range of a series of commercially available reagents spans more than two orders of magnitude. Selectfluor^TM (=1‐(chloromethyl)‐4‐fluoro‐1,4‐diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate); 9 ; also called F‐TEDA; TEDA=triethylenediamine) reacts more than 100 times faster than 1‐fluoropyridinium tetrafluoroborate.     

Etude par RMN protonique d'heterocycles voisins de l'oxazaphospholane-1,3,2. II—Le diméthylamino-2 méthyl-3 oxazaarsolane-1,3,2

The ¹H NMR spectrum of the 2-dimethylamino-3-methyl 1,3,2 oxazaarsolane is very sensitive to solvent and temperature. A complete analysis of the spectrum at ?48 °C in deuteriated toluene shows that the molecule exists in a preferred conformation in the C-4? C-5 region. The spectrum, corresponding to an A₂X₂ system in nitrobenzene at +31 °C, indicates free movement around that bond. At higher temperatures a new coalescence phenomenon is explained by inversion of the As atom.     

Heterocycles Contenant du Phosphore—V. Analyse des Spectres de Resonance Magnetique Protonique des Oxo-2 Methoxy ou Phénoxy-2, Methyl-3, Oxazaphospholanes-1,3,2: Exemples de Spectres du type ABXY

The ³¹P decoupled PMR spectra of the title oxazaphospholanes give rise to well resolved ABXY patterns. Among the eight possible solutions, six can be readily eliminated from chemical shifts considerations and the choice between the remaining two is based on tickling experiments. Good fits are observed between experimental and calculated spectra. The relative signs of the ³J(P? O? C? H) and ³J(P? N? C? H) coupling constants are given by tickling and Indor experiments. The ring conformation is discussed.     

Photochromism Emergence in N‐Salicylidene p‐Aminobenzenesulfonate Diallylammonium Salts

N‐Salicylidene p‐aminobenzenesulfonate salts were prepared by in situ condensation of p‐aminobenzenesulfonate diallylammonium salt and salicylaldehyde. Modulation of thermo‐ and photochromism was achieved by varying the alkyl chain length of the diallylammonium counter‐cation. A structural–optical properties investigation reveals that both crystal packing and dihedral angle between aromatic rings of the N‐salicylidene aniline switch are not sufficient to predict the occurrence of photochromism in the solid state. The available free space around the N‐salicylidene p‐aminobenzenesulfonate, in addition to the flexibility of the nearby environment, is shown to be of major importance for the cis→trans isomerisation to occur as well as for the stabilisation of the trans‐keto form. Emergence of photochromic properties was determined from the diallylhexylammonium cation within the series of investigated counter‐cations. High stability is observed for the trans‐keto form of one polymorph of N‐salicylidene p‐aminobenzenesulfonate diallylhexylammonium salt (k=2.4×10^?7 s^?1).