Palladium-catalyzed cross-coupling of H-phosphinate esters with chloroarenes

The palladium-catalyzed cross-coupling reaction between H-phosphinate esters and chloroarenes or chloroheteroarenes is described. This reaction is the first general metal-catalyzed phosphorus-carbon bond-forming reaction between a phosphorus nucleophile and chloroarenes.     

Multivalent RGD synthetic peptides as potent alphaVbeta3 integrin ligands

We study herein the multivalency effect of a cluster of alphaVbeta3-ligands held on a cyclodecapeptide template. An array of RAFT(c[-RGDfK-])n derivatives containing from one to sixteen clustered RGD motifs were synthesized and comparatively assayed in vitro on alphaVbeta3-expressing cells. Efficient inhibition of the alphaVbeta3-specific 23C6 monoclonal antibody fixation was observed with ligands displaying three and four copies of the cyclo[-RGDfK-] peptide.     

Thermoelectrets formed by the phase transition in cholesteryl caproate and its derivatives

Phase transitions have been measured by the thermodielectric effect, i.e. by the production of thermoelectrets in liquid crystals when cooling the samples from the isotropic state to the solid state. By recording the current across the samples as a function of temperature it is possible to specify very exactly the temperature at which the isotropic-liquid crystal phase transition begins.     

Improved Syntheses of 3,17β-Diacetoxyestra-1,3,5(10)-Trien-6-One

improved syntheses of 3,17β-Diacetoxyestra-1,3,5(10)-trien-6-one 5 was achieved in 4 steps (respectively in 45% and 56% overall yield) from 19-nortestosterone 1.     

Surface and interfacial segregation of polyethersulfone deuterated chain ends determined by neutron reflectivity

The surface localization of polymer chain ends has been shown to be an effective method for surface composition control in amorphous polymer films. This work determines chain end distribution in thin polyethersulfone (PESU) films end‐capped with deuterated compounds of varying size and composition. Neutron reflectivity revealed the preferential localization of chain ends to the PESU‐air interface, independent of chain end identity. The length scale of the chain end concentration gradient was determined to differ from that predicted for flexible chain polymers. Atomic force microscopy and contact angle analysis demonstrated that chain end localization allows for improved control of nanoscale and macroscale surface properties of PESU films. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 293–301     

DBU-promoted alkylation of alkyl phosphinates and H-phosphonates

The alkylation of alkyl phosphinates and some H-phosphonate diesters is promoted by the base DBU. Only more reactive alkyl halides react in preparatively useful yields. However, the method provides easy access to important H-phosphinate building blocks, without the need for a protecting group strategy or metal catalysts. The reaction is conveniently conducted at, or below, room temperature. The preparation of methyl-H-phosphinate esters is particularly interesting as it avoids the heretofore more common use of methyldichlorophosphine MePCl₂.     

Raman Spectrum of n-Propylamine in Cyclohexane

Polarized (Isotropic) Raman spectra of the N-H valence region of n-propylamine have been recorded as a function of concentration in cyclohexane. Statistical analysis of the data using non-linear least squares techniques revealed the presence of a fourth spectral band in this region, not observed in an earlier IR study. This latter peak has been assigned to vibrations of monomers in the liquid. The resolved spectral parameters are consistent with a picture of diminishing molecular association upon dilution of the amine in this non-polar solvent.