Search

Abstract: Lewis acid platinum and palladium complexes of (S)-Me2-CATPHOS catalyse the carbonyl-ene reaction between allylbenzene derivatives and ethyl trifluoropyruvate to give the expected α-hydroxy esters with ee’s up to 97%, while the corresponding reaction involving 2-allylfuran and thiophene was exclusively selective for Friedel–Crafts-type reactivity and gave the corresponding 2-hydroxy-trifluoromethyl ethyl esters in good yield and moderate to good enantioselectivity. [Copyright &y& Elsevier]

Abstract: Rhodium complexes of (R)-Me-CATPHOS and (R)-(S)-JOSIPHOS form a complementary pair of catalysts for the highly efficient asymmetric hydrogenation of a selection of (E)- and (Z)-β-aryl-β-(enamido)phosphonates, respectively, in the majority of cases giving excellent yields and ee’s in excess of 99%; the highest to be reported for this class of substrate. [Copyright &y& Elsevier]

Several novel phosphoramidites have been prepared by reaction of the primary amines para-vinylaniline, ortho-anisidine, 2-methoxyphenyl(4-vinylbenzyl)amine, 8-aminoquinoline and 3-vinyl-8-aminoquinoline with (S)-1,1′-bi-2-naphthylchlorophosphite, in the presence of base. Rhodium(I) complexes of these phosphoramidites catalyse the asymmetric hydrogenation of dimethylitaconate and dehydroamino acids and esters giving ee values up to 95%. Soluble non-cross linked polymers of the para-vinylaniline and 3-vinyl-8-aminoquinoline-based phosphoramidites have been prepared by free radical co-polymerisation with styrene in the presence of AIBN as initiator. The corresponding [Rh(COD)]+ complexes serve as recyclable catalysts for the asymmetric hydrogenation dimethylitaconate and dehydroamino acids and esters to give ee values up to 80%. [Copyright &y& Elsevier]

• Ultrafine RuNPs are stabilised by amino-modified polymer immobilized ionic liquid. • High activity for hydrolytic evolution of hydrogen from NaBH 4. • Kinetic studies confirm the hydrolysis is first order in catalyst and hydride. • Kinetic isotope studies with H 2 O/D 2 O and NaBH 4 /NaBD 4 support the proposed mechanism. • High activity retained over five reuses with only a minor reduction in conversion. Ruthenium nanoparticles stabilised by polymer immobilized ionic liquids catalyse the hydrolytic release of hydrogen from sodium borohydride. The composition of the polymer influences performance and ruthenium nanoparticles stabilised by an amine-decorated imidazolium-based polymer immobilised ionic liquid (RuNP@NH 2 -PIILS) was the most efficient with a maximum initial turnover frequency (TOF) of 177 mole H2.mol Ru −1.min−1, obtained at 30°C with a catalyst loading of 0.08 mol%; markedly higher than that of 69 mol H2.mol Ru −1.min−1 obtained with 5 wt% Ru/C and one of the highest to be reported for a RuNP catalyst. The apparent activation energy (Ea) of 38.9 kJ mol−1 for the hydrolysis of NaBH 4 catalysed by RuNP@NH 2 -PIILS is lower than that for the other polymer immobilized ionic liquid stabilised RuNPs, which is consistent with its efficacy. Comparison of the initial rates of hydrolysis in H 2 O and D 2 O catalysed by RuNP@NH 2 -PIILS gave a primary kinetic isotope effect (k H / k D) of 2.3 which supports a mechanism involving rate limiting oxidative addition of one of the O-H bonds in a strongly hydrogen-bonded surface-coordinated [BH 3 H−]—-H 2 O ensemble. The involvement of a surface-coordinated borohydride is further supported by an inverse kinetic isotope effect of 0.65 obtained from a comparison of the initial rates for the hydrolysis of NaBH 4 and NaBD 4 under the conditions of catalysis i.e., at a high hydride/catalyst mole ratio. Interestingly though, when the comparison of the initial rates of hydrolysis of NaBH 4 and NaBD 4 was conducted in dilute solution with a hydride/catalyst mole ratio of 1 a kinetic isotope effect (k H / k D) of 2.72 was obtained; this would be more consistent with concerted activation of both an O-H and B-H bond in the rate limiting step, possibly via a concerted oxidative addition-hydride transfer in the surface-coordinated hydrogen-bonded ensemble. Catalyst stability and reuse studies showed that RuNP@NH 2 -PIILS retained 71% of its activity over five runs; the gradual drop in the initial TOF with run number appears to be due to passivation of the catalyst by the sodium borate by-product as well as an increase in viscosity of the reaction mixture rather than leaching of the catalyst. [Display omitted] [ABSTRACT FROM AUTHOR]

Vaccine adjuvants are typically designed to stimulate both systemic and mucosal immune responses. Polymeric nanoparticles have been used as adjuvants in the development of vaccines against a number of viral pathogens and tested in laboratory animals. The objective of the study was to assess if synthetic bovine parainfluenza virus type-3 (BPI3V) peptide motifs and solubilised BPI3V proteins encapsulated in poly (dl-lactic-co-glycolide) (PLGA) nanoparticles (NPs) induce specific humoral immune responses in a mouse model following intranasal administration. BPI3V-specific and peptide specific IgG ELISAs were used to measure serum IgG levels to BPI3V. Intranasal delivery of PLGA nanoparticles encapsulating BPI3V proteins elicited an early, gradually increasing BPI3V-specific IgG response that persisted over the subsequent 6 weeks, suggesting slow, persistent release of antigen. PLGA-BPI3V particles administered intranasally induced a stronger IgG antibody response at an earlier time point compared with solubilised BPI3V antigen alone. Such an approach could be deployed in the development of new generation vaccines. [ABSTRACT FROM AUTHOR]