Regioselective Hydrolysis of Cocaine and A Convenient Acylation Procedure by Benzoylecgonine

Regioselective hydrolysis of cocaine led, according to the reaction conditions, either to benzoylecgonine or to ecgonine methyl ester. Acylation with benzoylecgonine was readily achieved when benzotriazolyloxytrisdimethylamino-phosphonium (BOP) was used as a coupling agent.     

Internal Transfer Reactions in the Copolymerization of Vinyl Acetate with Chlorinated Monomers

In the copolymerization of vinyl acetate (A) with either vinyl chloride (C) or vinylidene chloride (V), an internal transfer (backbiting) reaction—of the C- or V-ended radi-cals on an antepenultimate A unit—is proposed to be responsible for the deviation of the copolymerization kinetics from the Lewis and Mayo theory. The deviations disappear if A is replaced by isopropenylacetate [I_p], Then one gets, for the I_p -C copolymerization. r_{I p} =0.35 and :r_c=2.4, and for I -V copolymerization, r_{I p}=0.13 and r_v=5.9. The internal transfer reaction causes the formation of branches which may be evidenced by NMR analysis of constant composition suspension A-C copolymers. A kinetic scheme is proposed and the corresponding reactivity ratios derived r_A=0.29, r_c=1.60, r=0.3 (radical resulting from the transfer reaction), and k_T=1500 (rate constant of the transfer reaction at 50°C). The distribution of branches is calculated together with the sequence distribution functions for the .A. or Cunits.     

Redox‐responsive core cross‐linked micelles of poly(ethylene oxide)‐b‐poly(furfuryl methacrylate) by Diels‐Alder reaction for doxorubicin release

Redox‐responsive core cross‐linked (CCL) micelles of poly(ethylene oxide)‐b‐poly(furfuryl methacrylate) (PEO‐b‐PFMA) block copolymers were prepared by the Diels‐Alder click‐type reaction. First, the PEO‐b‐PFMA amphiphilic block copolymer was synthesized by the reversible addition‐fragmentation chain transfer polymerization. The hydrophobic blocks of PFMA were employed to encapsulate the doxorubicin (DOX) drug, and they were cross‐linked using dithiobismaleimidoethane at 60 °C without any catalyst. Under physiological circumstance, the CCL micelles demonstrated the enhanced structural stability of the micelles, whereas dissociation of the micelles took place rapidly through the breaking of disulfide bonds in the cross‐linking linkages under reduction environment. The core‐cross‐linked micelles showed fine spherical distribution with hydrodynamic diameter of 68 ± 2.9  nm. The in vitro drug release profiles presented a slight release of DOX at pH 7.4, while a significant release of DOX was observed at pH 5.0 in the presence of 1,4‐dithiothreitol. MTT assays demonstrated that the block copolymer did not have any practically cytotoxicity against the normal HEK293 cell line while DOX‐loaded CCL micelles exhibited a high antitumor activity towards HepG2 cells. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3741–3750     

Cinchona based squaramide catalysed enantioselective Michael addition of α-nitrophosphonates to aryl acrylates: enantioselective synthesis of quaternary α-aminophosphonates

Several cinchona based squaramide catalysts were applied to the asymmetric Michael addition of α-nitroethylphosphonates to acrylic acid aryl esters, resulting in high yields and enantioselectivities. The absolute configuration of one of the quaternary α-nitrophosphonate adducts was deduced from its experimental and calculated CD spectra. The adducts were reduced to their cyclic aminophosphonates by catalytic hydrogenation.     

Oliveridepsidones A–D,antioxidant depsidones from Garcinia oliveri

Four new prenylated depsidones, oliveridepsidones A–D, were isolated from the bark of Garcinia oliveri collected in Vietnam. Their structures were elucidated using mainly NMR techniques (¹H and ¹³C NMR, HMQC, HMBC and NOE experiments). Copyright © 2012 John Wiley & Sons, Ltd.     

A splitting algorithm for equilibrium problem given by the difference of two bifunctions

In this paper, we introduce a splitting algorithm for solving equilibrium problems given by the difference of two bifunctions in a real Hilbert space. Under suitable assumptions on component bifunctions, we prove strong convergence of the proposed algorithm. In contrast to most existing projection-type methods for equilibrium problems, our algorithm does not require any convexity or monotonicity conditions on the resulting bifunction. Some numerical experiments and comparisons are given to illustrate the efficiency of the proposed algorithm.     

Self-adaptive gradient projection algorithms for variational inequalities involving non-Lipschitz continuous operators

Numerical Algorithms - In this paper, we introduce a self-adaptive inertial gradient projection algorithm for solving monotone or strongly pseudomonotone variational inequalities in real Hilbert...