Palladium-Mediated C(sp3)-H Bond Activation of N-Methyl-N-(pyridin-2-yl)benzamide: Direct Arylation/Alkylation and Mechanistic Investigation.

Herein, we present a facile synthetic methodology to produce a range of N-(CH2-aryl/alkyl)-substituted N-(pyridin-2-yl)benzamides via palladium-mediated C(sp3)-H bond activation. The N-methyl-N-(pyridin-2-yl)benzamide precursor was first reacted with palladium(II) acetate in a stoichiometric manner to obtain the key dinuclear palladacycle intermediates, whose structures were elucidated by mass spectrometric, NMR spectroscopic, and X-ray crystallographic studies in detail. The subsequent C(sp3)-H bond functionalizations on the N-methyl group of the starting substrate show facile productions of the corresponding N-(CH2-aryl/alkyl)-substituted N-(pyridin-2-yl)benzamides with good functional group tolerance. A plausible mechanism was proposed based on density functional theory calculations in conjunction with kinetic isotope effect experiments. Finally, the synthetic transformation from the prepared N-(CH2-aryl)-N-(pyridin-2-yl)benzamides through debenzoylation to N-(CH2-aryl)-2-aminopyridine was successfully demonstrated.

Nanocellulose-based hydrogels for drug delivery.

Hydrogels, as a class of three-dimensional (3D) polymer networks, are important candidates for drug delivery owing to their high porosity and hydrophilicity. Generally, clinical applications put forward various requirements for drug delivery systems (DDSs), such as low toxic side effects, high biocompatibility, targeting, controllable release, and high drug loading. In recent years, nanocellulose, including cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs), has emerged as a promising material for hydrogel-based DDSs. This is due to its high surface area, abundant surface hydroxyl groups that can be easily chemically modified for multifunctionalization, natural origin leading to high biocompatibility and degradability, etc. This review provides a comprehensive overview of the preparation methods for hydrogels based on CNCs/CNFs for use in drug delivery systems, including physical crosslinking and chemical crosslinking. Additionally, various carrier forms such as hydrogel particles, hydrogel films, injectable hydrogels, and sprayable hydrogels are discussed. Key drug delivery parameters including loading and release efficiency as well as responses to different stimuli are also examined in detail. Finally, in view of the subdivision of drug delivery, the opportunities and challenges of nano cellulose based hydrogels were proposed from the perspective of application, and the potential research directions were pointed out.

The Ending Effect in Investment Decisions: The Motivational Need for an Emotionally Rewarding Ending.

The present study examined the power of endings on risky decision making. With four experiments, the changes in the individuals' risk-taking tendencies were examined as the end of an investment decision task approached; the role of motivational shift toward emotional satisfaction in the ending effect was also explored. As predicted, participants who knew they were working on the last round of an investment task were more risk seeking than those who did not know (i.e., ending effect, Experiment 1). Experiments 2 through 4 examined the motivational mechanism of the ending effect. The results supported the notion that the motivation to pursue an emotionally rewarding ending leads to the ending effect. The present research complements existing motivational accounts of risk taking and suggests a new research direction of integrating factors associated with time perception of an approaching ending into existing models of risky decision making.