Stereoselective Synthesis of (–)-Heliannuol E by α-Selective ­Propargyl Substitution

This paper describes a stereoselective synthesis of (–)-heliannuol E through intramolecular cyclization of a phenol mesylate. The introduction of the aromatic group was achieved by α-selective propargyl substitution of a propargylic phosphate.

Characterization of Different Salt Forms of Chitooligosaccharides and Their Effects on Nitric Oxide Secretion by Macrophages

In this paper, chitooligosaccharides in different salt forms, such as chitooligosaccharide lactate, citrate, adipate, etc., were prepared by the microwave method. They were characterized by SEM, FTIR, NMR, etc., and the nitric oxide (NO) expression was determined in RAW 264.7 cells. The results showed that pure chitooligosaccharide was an irregular spherical shape with rough surface, and its different salt type products are amorphous solid with different honeycomb sizes. In addition to the characteristic absorption peaks of chitooligosaccharides, in FTIR, the characteristic absorption of carboxyl group, methylene group, and aromatic group in corresponding acid appeared. The characteristic absorption peaks of carbon in carboxyl group, hydrogen and carbon in methyl, methylene group, and aromatic group in corresponding acid also appeared in NMR. Therefore, the sugar ring structure and linking mode of chitooligosaccharides did not change after salt formation of chitooligosaccharides. Different salt chitooligosaccharides are completely different in promoting NO secretion by macrophages, and pure chitooligosaccharides are the best.

A Photocatalytic Regioselective Hydroaminoalkylation of Aryl-Substituted Alkenes with Simple Amines

A photocatalytic method for the alpha-selective hydroaminoalkylation of cinnamate esters has been developed. The reaction involves the regioselective addition of alpha-aminoalkyl radicals generated from aniline derivatives or aliphatic amines to the alpha-position of unsaturated esters. The scope of aromatic alkenes was extended to styrenes undergoing hydroaminoalkylation with anti-Markovnikov selectivity, which confirms the importance of the aromatic group at the beta-position. Simple scale-up is demonstrated under continuous-flow conditions, highlighting the practicality of the method.<br>

A Photocatalytic Regioselective Hydroaminoalkylation of Aryl-Substituted Alkenes with Simple Amines

A photocatalytic method for the alpha-selective hydroaminoalkylation of cinnamate esters has been developed. The reaction involves the regioselective addition of alpha-aminoalkyl radicals generated from aniline derivatives or aliphatic amines to the alpha-position of unsaturated esters. The scope of aromatic alkenes was extended to styrenes undergoing hydroaminoalkylation with anti-Markovnikov selectivity, which confirms the importance of the aromatic group at the beta-position. Simple scale-up is demonstrated under continuous-flow conditions, highlighting the practicality of the method.<br>

The Critical Role of Aromatic-Aromatic Drug-Polymer Interactions to Provide Nanomedicines Containing Chloroquine: A Simple Proposal to Provide High Encapsulation, High Stability, and Prolonged Drug Release

Background: Chloroquine (CQ) is a drug commonly used to treat malaria. CQ has also gained interest for the treatment of other chronic diseases such as arthritis, lupus, cancer, diabetes, atherosclerosis, and dermatomyositis, among others. Since CQ is hydrophilic and low molecular-weight, attractive interactions with polymers in aqueous medium are weaker than with water, so that low encapsulation together with uncontrolled and fast release is observed. Importantly, a long-term administration of CQ is suggested, thus the development of formulations with controlled and prolonged release is desirable. Results: Here we propose the use of aromatic interactions between the cationic CQ and the FDA approved polymer poly(sodium 4-styrenesulfonate) (PSS) for the formation and stabilization of nanoparticles (NPs). The strategy consists on the simple mixture of two aqueous solutions containing the oppositelly charged molecules. UV-vis and NMR spectroscopy evidence intimate aromatic-aromatic interactions between CQ and PSS. CQ/PSS molar ratios from 0.2 to 0.5 allow obtaining NPs with spherical shape, size in the range of 170-410 nm, zeta potential from -18 to -45 mV, and particles number in the range of 0.9 - 6.6 x 1010 NPs/mL. Selected NPs (CQ/PSS molar ratio 0.4) are stable to wide variations in ionic strength (0-200 mM), pH (2-10) and temperature (20-50 °C). In addition, CQ/polymer 0.4 was also tested but with the absence of the aromatic group in the polymer, and providing smaller (70 nm), lower-concentrated (6.1 x 109 NPs/mL), and unstable particles, confirming the key role of the aromatic group. Furthermore, CQ/PSS NPs are stable during months and can be converted to a reconstitutable powder. Importantly, the selected NPs (CQ/PSS 0.4) show full drug association efficiency (100 %), very high drug loading (49 %), very high yield (89 %), and evidencing a drug entrapment/release governed by kinetic associations (≈99 %). Finally, release studies evidence a controlled and prolonged delivery. Conclusions: Considering the potential uses of CQ for chronic diseases, and the simplicity and efficiency of our proposal, it could be considered as a valuable alternative to developed nanomedicines. In addition, this strategy could be used for other drugs and polymers showing similar characteristics to CQ and PSS.