Enhanced Performance of Blended Polymer Excipients in Delivering a Hydrophobic Drug through the Synergistic Action of Micelles and HPMCAS.

Blends of hydroxypropyl methylcellulose acetate succinate (HPMCAS) and dodecyl (C)-tailed poly(N-isopropylacrylamide) (PNIPAm) were systematically explored as a model system to dispense the active ingredient phenytoin by rapid dissolution, followed by the suppression of drug crystallization for an extended period. Dynamic and static light scattering revealed that C-PNIPAm polymers, synthesized by reversible addition-fragmentation chain-transfer polymerization, self-assembled into micelles with dodecyl cores in phosphate-buffered saline (PBS, pH 6.5).

Ti-Catalyzed Multicomponent Oxidative Carboamination of Alkynes with Alkenes and Diazenes.

The inter- or intramolecular oxidative carboamination of alkynes catalyzed by [pyTiClNPh] is reported. These multicomponent reactions couple alkenes, alkynes and diazenes to form either α,β-unsaturated imines or α-(iminomethyl)cyclopropanes via a Ti/Ti redox cycle. Each of these products is formed from a common azatitanacyclohexene intermediate that undergoes either β-H elimination or α,γ-coupling, wherein the selectivity is under substrate control.

Permeability of Rubbery and Glassy Membranes of Ionic Liquid Filled Polymersome Nanoreactors in Water.

Nanoemulsion-like polymer vesicles (polymersomes) having ionic liquid interiors dispersed in water are attractive for nanoreactor applications. In a previous study, we demonstrated that small molecules could pass through rubbery polybutadiene membranes on a time scale of seconds, which is practical for chemical transformations. It is of interest to determine how sensitive the rate of transport is to temperature, particularly for membranes in the vicinity of the glass transition (Tg).

Mechanistic study of the stereoselective polymerization of D,L-lactide using indium(III) halides.

We report the results of a comprehensive investigation of the recently discovered stereoselective and controlled polymerization of racemic lactide (D,L-LA) using an initiator prepared in situ from indium(III) chloride (InCl(3)), benzyl alcohol (BnOH), and triethylamine (NEt(3)). Linear relationships between number-average molecular weight (M(n)) and both monomer to alcohol concentration ratio and monomer conversion are consistent with a well-controlled polymerization. Studies on polymerization kinetics show the process to be first-order in [InCl(3)](0) and zero-order in both [BnOH](0) and [NEt(3)](0).

Electrochemistry in Media of Exceptionally Low Polarity: Voltammetry with a Fluorous Solvent.

This work demonstrates the first cyclic voltammetry in a perfluorocarbon solvent without use of a cosolvent. The novel electrolyte tetrabutylammonium tetrakis[3,5-bis(perfluorohexyl)phenyl]borate (NBu(4)BArF(104); 80 mM) allows for voltammetry of ferrocene in perfluoro(methylcyclohexane) by lowering the specific resistance to Ω268 k cm at 20.8 °C.

Structural and mechanistic studies of bis(phenolato)amine zinc(II) catalysts for the polymerization of epsilon-caprolactone.

The syntheses, characterization, epsilon-caprolactone (CL) polymerization activity, and kinetics investigation of two zinc(II) bis(phenolato)amine complexes L2Zn2 are reported (L = methylamino-N,N-bis(2-methylene-4,6-di-tert-butylphenolato) and/or methylamino-N,N-bis(2-methylene-4-adamantyl-6-tert-butylphenolato)). X-ray crystallographic and 1H NMR studies, including NOESY and PGSE experiments, provided insight into the solid and solution state structures, respectively, as well as evidence for the catalytically active species responsible for the ring-opening polymerization of CL. Additionally, solution polymerizations and kinetic experiments involving (L1)2Zn2 in the presence of benzyl alcohol (BnOH) were performed to elucidate the influence of catalyst structure, solvent, and the concentration dependence of the catalytically active species, CL, and BnOH on the rate and control of poly-epsilon-caprolactone (PCL) formation.

No-D NMR (no-deuterium proton NMR) spectroscopy: a simple yet powerful method for analyzing reaction and reagent solutions.

[reaction: see text] The title technique is a convenient and powerful method for directly monitoring or assaying any reaction mixture or reagent solution. Examples of some common processes (Fischer esterification, lithiation, butyllithium/THF compatibility, olefin metathesis, and a quantification assay), each interrogated in its native solvent, are presented. The spectral data are easy to acquire, and the information content makes a compelling case for routine use of No-D NMR spectroscopy.

NMR studies on epoxidations of allenamides. Evidence for formation of nitrogen-substituted allene oxide and spiro-epoxide via trapping experiments.

Two epoxidations of chiral allenamides are described here. While treatment with m-CPBA led to highly stereoselective formation of an alpha-keto aminal that can be useful synthetically, DMDO oxidation led to conclusive evidence for both nitrogen-substituted allene oxide (via mono-epoxidation) and spiro-epoxide (via bis-epoxidation) using intramolecular nucleophilic trapping experiments. NMR studies provide reliable evidence for a 3-oxetanone that can be derived from the spiro-epoxide and also suggest the presence of an allene oxide.