Aluminium triflate, a relatively new addition to the family of metal triflates, showcases a distinctive reactivity profile that sets it apart from traditional Lewis acids such as aluminium chloride (AlCl3), tin (IV) chloride (SnCl4), and boron trifluoride (BF3). Its unique properties make it an attractive candidate for various catalytic applications. Notably, aluminium triflate can be easily prepared and utilised at low catalyst loadings, enhancing its efficiency and cost-effectiveness. Furthermore, its recyclability contributes to sustainable practices, aligning perfectly with the principles of green chemistry. The solubility and stability of aluminium triflate in aqueous media further enhance its appeal, as these characteristics allow for more environmentally friendly reaction conditions. Compared to other catalytic systems, Al(OTf)3 exhibits consistently superior performance, particularly in terms of selectivity and turnover frequency. This superior reactivity makes it a powerful tool in organic synthesis, enabling chemists to achieve desired transformations with greater precision and efficiency. In this comprehensive review, we explore the significant advancements in the application of aluminium triflate as a catalyst in organic transformations from 1985 to 2024. We highlight key studies that demonstrate its versatility across various reaction types, including the formation of carbon-carbon and carbon-heteroatom bonds. This critical analysis of advancements in this field aims to provide insights into the future potential of aluminium triflate in organic synthesis and its role in advancing sustainable chemistry practices.

Tuberculosis (TB) continues to be a threat to global health stability. Pyrimidine carboxamides have demonstrated potent anti-tubercular properties against clinical Mycobacterium tuberculosis, the causative agent of TB. Herein, we report a follow-up study on the synthesis of pyrimidine carboxamide molecular analogues and their anti-TB evaluation. In total, a library consisting of 37 new compounds is reported. Seven compounds (7b, 7d, 7m, 7p, 7q, 7aa, and 7ah) demonstrated excellent in vitro activities with MIC90 values below 1.00 µM. Apart from compound 7ah, compounds with improved aqueous solubility properties had lower anti-TB potency. Preliminary mode of action studies using bioluminescence assays indicate that the active compounds do not affect the integrity of mycobacterial DNA or the cell wall. The active compounds were also found to be bactericidal against replicating H37Rv Mtb strain.

The aim of the study was to isolate and characterise antimicrobial agents from the leaves of Capparis fascicularis using thin-layer chromatography-direct bioautography (TLC-DB). Capparis fascicularis is a medicinal plant used traditionally to treat various ailments. Previous studies have shown that species of the genus Capparis, contain several classes of secondary metabolites, including sterols. In this study, the leaves of C. fascicularis were extracted with 80% aqueous methanol, and the extract’s fractions were screened for antimicrobial activity against Staphylococcus aureus ATCC 25923 using a broth micro-dilution assay. The hexane fraction was the most active, with a minimum inhibitory concentration (MIC) of 512 µg/mL. TLC-DB and flash column chromatography of the hexane fraction resulted in the isolation of β-Sitosterol for the first time from C. fascicularis. The compound was characterised using NMR and HRMS.

Phenotypic screening of a Medicines for Malaria Venture compound library against Mycobacterium tuberculosis (Mtb) identified a cluster of pan-active 2-pyrazolylpyrimidinones. The biology triage of these actives using various tool strains of Mtb suggested a novel mechanism of action. The compounds were bactericidal against replicating Mtb and retained potency against clinical isolates of Mtb. Although selected MmpL3 mutant strains of Mtb showed resistance to these compounds, there was no shift in the minimum inhibitory concentration (MIC) against a mmpL3 hypomorph, suggesting mutations in MmpL3 as a possible resistance mechanism for the compounds but not necessarily as the target. RNA transcriptional profiling and the checkerboard board 2D-MIC assay in the presence of varying concentrations of ferrous salt indicated perturbation of the Fe-homeostasis by the compounds. Structure-activity relationship studies identified potent compounds with good physicochemical properties and in vitro microsomal metabolic stability with moderate selectivity over cytotoxicity against mammalian cell lines.

Amide functional groups are prominent in a broad range of organic compounds with diverse beneficial applications. In this work, we report the synthesis of these functional groups via an iron(iii) chloride-catalyzed direct amidation of esters. The reactions are conducted under solvent-free conditions and found to be compatible with a range of amine and ester substrates generating the desired amides in short reaction times and good to excellent yields at a catalyst loading of 15 mol%.

The amide functional group is common in natural and synthetic products.Its prevalence in fine chemicals and pharmaceuticals has propelled a surge in the development of new synthesis procedures to access this amide bond.Nitroarenes are key building blocks in organic synthesis and are easily accessible via nitration of parent arenes.This review highlights the use of nitroarenes as alternatives to access the amide functional group.A broad range of reductive amidation reactions and their proposed mechanistic pathways are discussed.

Tuberculosis (TB) is one of the world’s most deadly infectious diseases, causing 1.2 million deaths in 2018. TB is the leading cause of death from a single infectious agent, ahead of HIV/AIDS. The African continent bears the highest global TB/HIV burden and over 50% of TB cases in sub-Saharan Africa are co-infected with HIV. With an estimated 1.7 billion people (23% of the world’s population) with latent TB infection, there is an urgent need to develop drugs that will eradicate or control the disease. Moreover, the emergence of multi-drug resistant tuberculosis (MDR-TB) and extensively drug resistant tuberculosis (XDR-TB) have accelerated the need for new antitubercular agents with novel biological targets and different mechanism of action. Among the wide spectra of heterocyclic compounds, benzopyran derivatives have displayed diverse biological applications.

A BioFocus DPI SoftFocus library of ∼35 000 compounds was screened against Mycobacterium tuberculosis (Mtb) in order to identify novel hits with antitubercular activity. The hits were evaluated in biology triage assays to exclude compounds suggested to function via frequently encountered promiscuous mechanisms of action including inhibition of the QcrB subunit of the cytochrome bc1 complex, disruption of cell-wall homeostasis, and DNA damage. Among the hits that passed this screening cascade, a 6-dialkylaminopyrimidine carboxamide series was prioritized for hit to lead optimization. Compounds from this series were active against clinical Mtb strains, while no cross-resistance to conventional antituberculosis drugs was observed. This suggested a novel mechanism of action, which was confirmed by chemoproteomic analysis leading to the identification of BCG_3193 and BCG_3827 as putative targets of the series with unknown function. Initial structure-activity relationship studies have resulted in compounds with moderate to potent antitubercular activity and improved physicochemical properties.

The bridged chiral benzopyrans were strategically ring opened via acetolysis to yield either galactose based chromenes or chromans, depending on the reaction conditions. A proposal relating to the mechanism of this selective ring opening acetolysis is discussed. The benzopyrans (chromenes, chromans and bridged chiral benzopyrans) were de-acetylated via triethyl amine catalysed transesterification. Interestingly, the chromenes did not yield the anticipated hydrolysis product (triol) but a new class of bridged chiral benzopyrans which were a result of intramolecular oxa-Michael addition. A chromene that formed during the selective ring opening of the bridged chiral benzopyrans was employed to develop a method for the synthesis of a carbohydrate derived oxepane. The oxepane synthesis was achieved, albeit in the face of numerous challenges from side reactions. The difficulties encountered in the synthesis are discussed...

3,4,6-Tri-O-acetyl-D-galactal is selectively converted into 1-O-aryl-2-deoxy derivatives or chiral bridged benzopyrans under Al(OTf)3 catalysis, depending on reaction conditions. The benzopyrans react with Al(OTf)3/acetic anhydride in ring-opening reactions in the absence or presence of acetic acid to selectively produce chiral chromenes or chromans, respectively, in high yields.

A temperature-controlled mechanism switch between the Al(OTf)(3)-catalysed direct addition of alcohols or the Ferrier rearrangement reactions in some glycals is presented. The scope and limitations are investigated as are the influence of the stereochemistry and nature of the protecting groups on the glycal substrate.

AbstractThe reaction of benzyl protected glycal (I) with both aliphatic and aromatic alcohols in the presence of Al(O‐Tf)3 proceeds either via addition or via Ferrier rearrangement depending on the reaction temperature.

A simple and efficient method for the conversion of alcohols and phenols into their corresponding THP and THF ethers at room temperature has been developed using 1mol% aluminium triflate as catalyst. The deprotection reaction in the presence of methanol using Al(OTf)3 was equally successful and could be performed at ambient temperature in high yields.

AbstractEffective protection and deprotection is achieved for a wide range of alcohols and phenols using the same catalytic system and only changing CH2Cl2 as a solvent for protection to MeOH for deprotection.