Application of chitosan matrix for delivery of rutin

Chitosan matrices are an alternative material to the food industry, due to its ability to release bioactive compounds through interconnected cavities. Chitosan is a biomaterial of excellence, because it shows unique features, such as biocompatibility, non-toxicity, bactericidal action and the ability to associate with other compounds. Thus, this study aimed the development of chitosan matrices incorporated with rutin, as well as the evaluation of rutin release. Chitosan matrices with rutin were prepared by the coacervation method in alkaline solution and subsequently characterized through FT-IR, TG-DSC, X-ray diffraction, SEM and further submitted to rutin release assay. Results show the effectiveness in the incorporation of rutin into the polymeric matrix. The polymeric matrix with rutin can quickly release it, which provides a wide range of applications, such as carrier of rutin as a micronutrient food additive.     

Synthesis of α-alkenyl-α-amino esters via addition of potassium Alkenyltrifluoroborate salts to imine in the presence of Yb(OTf)3

A simple protocol which led to an effective construction of α-alkenyl-α-amino esters was achieved under mild conditions. This transformation proceeded by Yb-catalyzed addition of alkenyltrifluoroborates across the imine double bond. A variety of functional groups could be applicable to both partners.     

Functionalization of 2-(S)-isopropyl-5-iodo-pyrimidin-4-ones through Cu(I)-mediated 1,3-dipolar azide-alkyne cycloadditions

A series of 2-(S)-isopropyl-pyrimidinones functionalized at C5 with triazole rings, in which the substituents are found at N-1′ of the triazole ring, were synthesized. Through the azide-acetylene cycloaddition reaction, using CuI as a copper source and ultrasonic waves as an energy source it was possible to obtain products with yields ranging from 79% to 89% within 5 min or less. A preliminary study to gain further insight into the reaction was performed using in situ ReactIR technology.     

Ultrasound-assisted addition of alcohols to N-acyliminium ions mediated by In(OTf)3 and synthesis of 1,2,3-triazoles

An easy and mild approach using ultrasound-assisted reaction addition of alcohols to N-acyliminium ion mediated by Lewis acid, In(OTf)₃, allowed the synthesis of ether pyrrolidinones; next, the products were converted to 1,2,3-triazoles using click chemistry reaction conditions. The products in both reactions were afforded in moderate to good yields.     

Synthesis of functionalized N-triazolyl maleimides

An easy and mild two-step one-pot reaction allowed the synthesis of functionalized N-triazolyl maleimide. Next, the addition of propargyl alcohol and propargyl amine to the N-acyliminium ion mediated by Lewis acid, In(OTf)₃, allowed the introduction of a second 1,2,3-triazol ring at position 5 of the amide. The products in both reactions were achieved in moderate to good yields.     

Synthesis of symmetrical 1,3-diynes via homocoupling reaction of n-butyl alkynyltellurides

An ultrasound-assisted synthesis of symmetrical 1,3-diyne compounds with electron-withdrawing or -donating substituents is described and illustrated by the palladium-catalyzed homocoupling reaction of n-butyl alkynyltellurides. This procedure offers easy access to 1,3-diynes in very short reaction times, and the products are achieved in good to excellent yields.     

Negishi cross-coupling of organotellurium compounds: synthesis of biaryls, aryl-, and diaryl acetylenes

A functional group tolerant palladium-catalyzed Negishi coupling of diaryl tellurides with organozinc has been developed. This methodology permits efficient preparation of biaryls, aryl acetylenes and diaryl acetylenes in moderate to good yields. A preliminary study to gain further insight into the reaction was performed using in situ ReactIR technology.     

Computational Insights of Selective Intramolecular O-atom Transfer Mediated by Bioinspired Copper Complexes

The stereoselective copper-mediated hydroxylation of intramolecular C−H bonds from tridentate ligands is reinvestigated using DFT calculations. The computational study aims at deciphering the mechanism of C−H hydroxylation obtained after reaction of Cu(I) precursors with dioxygen, using ligands bearing either activated ( L¹ ) or non-activated ( L² ) C−H bonds. Configurational analysis allows rationalization of the experimentally observed regio- and stereoselectivity. The computed mechanism involves the formation of a side-on peroxide species ( P ) in equilibrium with the key intermediate bis-(μ-oxo) isomer ( O ) responsible for the C−H activation step. The P/O equilibrium yields the same activation barrier for the two complexes. However, the main difference between the two model complexes is observed during the C−H activation step, where the complex bearing the non-activated C−H bonds yields a higher energy barrier, accounting for the experimental lack of reactivity of this complex under those conditions.