Synthesis of 6- and 7-acyl-4H-benzothiazin-3-ones

Synthesis of 6- and 7-substituted benzoxazin-3-ones was already described in the literature by acylation of the corresponding benzoxazin-3-ones or cyclization of the corresponding 4- or 5-acyl-2-aminophenols. This paper describes original synthetic pathways to afford the 6- and 7-acyl products in the benzothiazin-3-one series, respectively, via Stille coupling reaction and by acylation.     

A novel rearrangement reaction. A single-step conversion of tetrahydro-1-isoquinolinecarboxylic acids into 1-isoquinolones

The preparation of 2-acyl-6,7-dimethoxy-1,2,3,4-tetrahydro-1-isoquinolinecarboxamides is described. The mixed anhydride of 2-acyl-6,7-dimethoxy-1,2,3,4-tetrahydro-1-isoquinolinecarboxylic acid with isobutyl chloroformate was reacted with the corresponding hydrazines at — 10, — 15°. Besides those compounds, isoquinolones occur through a new side reaction. The structure of those products was established by ¹³C and ¹H nmr and mass spectroscopy. A possible mechanism of the reaction is discussed.     

New access to 4-phenyl-6H-pyrrolo[1,2-a]thieno[3,2-f]-[1,4]diazepines

Pyrrolo[1,2-a]thieno[3,2-f][1,4]diazepines were obtained in an original one step synthesis by treatment of imines 1 with paraformaldehyde in refluxing ethanol. The intermediate Mannich bases were also converted into the thienooxadiazocines 12 and the diazepine N-oxide 13 .     

Streaming current measurements in zirconia-coated capillaries

The electroosmotic flow created in zirconia-modified capillaries has been previously investigated. In this paper, we compared the electroosmotic data set with streaming current measurements and we related all these data through zeta-potential. Streaming current measurements give an excellent indication on the direction and the value of the electroosmotic mobility of an electrolyte/capillary system for a large set of experimental conditions: 2 < pH < 12, 0 < ACN < 80 %, 10(-4) M < [SO(2- )4 ] < 4 x 10(-2) M. A good correlation between zeta-potential from streaming current measurements and zeta-potential from electroosmotic mobility measurements was observed (r2 = 0.95). However, the values obtained from streaming current were always slightly lower than the one calculated from electroosmotic mobility (slope = 0.86, sigma = 0.06). In zirconia-coated capillaries the zeta-potential can be tuned from -50 to +100 mV depending on the composition of the electrolyte.     

Interactions of hairy latex particles with cationic copolymers

Interactions between polycations and core-corona particles are governed by ion-exchange reactions, entropically favored by the release of counterions. This complexation process allows the chains to penetrate into the shell, leading to adsorbed amounts greater than 1 mg m(-2). The destabilization occurs quickly, the domain of flocculation becomes larger when the concentration of monovalent salts is increased, and aggregates are composed of small and very compact clusters in a more or less self-similar structure at large scale. The adsorption of copolymers of low cationicity is characterized by still larger adsorbed amounts and layers thicker than the radius of gyration of the macromolecules. Depending on the charge content, the enhancement of the ionic strength can either promote the destabilization of the suspension or conversely induce the desorption of the chain. In pure water the structure of the flocs is long-range ordered and it becomes more heterogeneous in ionic media.     

Phosphinine stabilised gold nanoparticles; synthesis and immobilisation on mesoporous materials

The first synthesis of gold nanoparticles stabilised by a sub-stoichiometric amount of sp(2) phosphorus containing ligands was performed, as well as their immobilisation on mesostructured silica and titania hosts.     

Conformational and thermodynamic studies of alkaline subhalides M2X (M = Li, Na, K, Rb; X = F, Cl, Br, I)

Alkaline subhalides M₂X (M = Li, Na, K, Rb; X = F, Cl, Br, I) were investigated using DMol software combined with thermostatistical techniques to obtain thermodynamic data for studying the stability of these subhalides. Validation of these results was checked by establishing a link with the experimental MX-M phase diagrams by a simple empirical relation.     

Benzaldehyde lyase-catalyzed enantioselective carboligation of aromatic aldehydes with mono- and dimethoxy acetaldehyde

[reaction: see text] Benzaldehyde lyase from the Pseudomonas fluorescens catalyzes the reaction of aromatic aldehydes with methoxy and dimethoxy acetaldehyde and furnishes (R)-2-hydroxy-3-methoxy-1-arylpropan-1-one and (R)-2-hydroxy-3,3-dimethoxy-1-arylpropan-1-one in high yields and enantiomeric excess via acyloin linkage. Aromatic aldehydes and benzoins are converted into enamine-carbanion-like intermediates prior to carboligation.     

The effects of supramolecular assembly on exciton decay rates in organic semiconductors

We present time-resolved photoluminescence measurements on two series of oligo-p-phenylenevinylene (OPV) materials that are functionalized with quadruple hydrogen-bonding groups. These form supramolecular assemblies with thermotropic reversibility. The morphology of the assemblies depends on the way that the oligomers are functionalized; monofunctionalized OPVs (MOPVs) form chiral, helical stacks while bifunctionalized OPVs (BOPVs) form less organized structures. These are therefore model systems to investigate the effects of supramolecular assembly, the effects of morphology, and the dependence of oligomer length on the radiative and nonradiative rates of pi-conjugated materials. The purpose of this work is to use MOPV and BOPV derivatives as model systems to study the effect of intermolecular interactions on the molecular photophysics by comparing optical properties in the dissolved phase and the supramolecular assemblies. A simple photophysical analysis allows us to extract the intrinsic radiative and nonradiative decay rates and to unravel the consequences of interchromophore coupling with unprecedented detail. We find that interchromophore coupling strongly reduces both radiative and intrinsic nonradiative rates and that the effect is more pronounced in short oligomers.     

2-Amino-6-iodo-4-tosyloxypyrimidine: a versatile key intermediate for regioselective functionalization of 2-aminopyrimidines in 4- and 6-positions

2-Amino-6-iodo-4-tosyloxypyrimidine, easily prepared from commercially available material, is a key intermediate for the preparation of differentially substituted 2-aminopyrimidines by means of sequenced Suzuki and/or Sonogashira reactions.