Reductive amination of ketones/aldehydes with amines using BH3N(C2H5)3 as a reductant

Spirobipyridine Ligand Enabled Iridium-Catalyzed Site-Selective C-H Activation via Non-Covalent Interactions

The selective borylation of specific C-H bonds in organic synthesis remains a formidable challenge. In this study, we present a novel spirobipyridine ligand that features a binaphthyl backbone. This ligand facilitates the iridium-catalyzed selective C-H borylation of benzene derivatives. The ligand is designed with "side-arm-wall" substituents that allow vicinal di- or multi-substituted benzene derivatives to approach metal center and effectively block other reactive sites by non-covalent interactions with substrates. The effectiveness of this strategy is demonstrated by the successful selective distal C-H activation of various alkaloids and its broad compatibility with functional groups.

Easy Access to Tertiary Amines from Carbonyl Compounds with Substituted Amine-Boranes: A Substrate, Catalyst, and Additive-Free Approach Under Mild Conditions

Tertiary amines are ubiquitous and play an essential role in organocatalysis, pharmaceuticals, and fine chemicals. Amongst various synthetic procedures known for their synthesis, the reductive amination of carbonyl compounds has been found to be a proficient method. Over the past few decades, different synthetic strategies for reductive amination have been developed. Most of them suffer from the use of transition metals and/or harsh reaction conditions. Herein, we present an efficient, operationally simple protocol for the chemoselective transformation of carbonyl compounds to tertiary amines under benign conditions. The strategy encompasses a broad substrate scope under the metal-free condition at room temperature and does not require any solvent. A detailed mechanistic investigation was performed with the aid of control experiments and computational study to shed light on the reaction pathway.

Catalytic Reductive Amination of Aromatic Aldehydes on Co-Containing Composites

The performance of a series of cobalt-based composites in catalytic amination of aromatic aldehydes by amines in the presence of hydrogen as well as hydrogenation of quinoline was studied. The composites were prepared by pyrolysis of CoII acetate, organic precursor (imidazole, 1,10-phenantroline, 1,2-diaminobenzene or melamine) deposited on aerosil (SiO2). These composites contained nanoparticles of metallic Co together with N-doped carboneous particles. Quantitative yields of the target amine in a reaction of p-methoxybenzaldehyde with n-butylamine were obtained at p(H2) = 150 bar, T = 150 °C for all composites. It was found that amination of p-methoxybenzaldehyde with n-butylamine and benzylamine at p(H2) = 100 bar, T = 100 °C led to the formation of the corresponding amines with the yields of 72–96%. In the case of diisopropylamine, amination did not occur, and p-methoxybenzyl alcohol was the sole or the major reaction product. Reaction of p-chlorobenzaldehyde with n-butylamine on the Co-containing composites at p(H2) = 100 bar, T = 100 °C resulted in the formation of N-butyl-N-p-chlorobenzylamine in 60–89% yields. Among the considered materials, the composite prepared by decomposition of CoII complex with 1,2-diaminobenzene on aerosil showed the highest yields of the target products and the best selectivity in all studied reactions.

Adhesive hydrogels in osteoarthritis: from design to application

Osteoarthritis (OA) is the most common type of degenerative joint disease which affects 7% of the global population and more than 500 million people worldwide. One research frontier is the development of hydrogels for OA treatment, which operate either as functional scaffolds of tissue engineering or as delivery vehicles of functional additives. Both approaches address the big challenge: establishing stable integration of such delivery systems or implants. Adhesive hydrogels provide possible solutions to this challenge. However, few studies have described the current advances in using adhesive hydrogel for OA treatment. This review summarizes the commonly used hydrogels with their adhesion mechanisms and components. Additionally, recognizing that OA is a complex disease involving different biological mechanisms, the bioactive therapeutic strategies are also presented. By presenting the adhesive hydrogels in an interdisciplinary way, including both the fields of chemistry and biology, this review will attempt to provide a comprehensive insight for designing novel bioadhesive systems for OA therapy.

Catalyst-free CO2 Hydrogenation with BH3NH3 in Water: DFT Mechanistic Insights

Extensive DFT calculations show that BH3NH3 may transfer dihydrogen to CO2 rather than HCO3- in water over a barrier of 25.9 kcal/mol, followed by faster hydride transfer from borate anions...