Heterogeneous catalysis is a crucial component of green chemistry. In this study, a series of polyacrylonitrile fiber (PANF) catalysts, specifically PANF-TBDs, were developed by immobilizing the commonly utilized super organic base 1,5,7-triazabicyclo [4.4.0] dec-5-ene (TBD) onto commercially accessible PANF. This novel catalyst facilitates the effective and eco-friendly one-pot synthesis of 2-amino-4H-chromene. Moreover, an investigation into the impact of modification density on the catalytic efficacy of PANF-TBDs have been conducted. It was observed that PANF-TBD(2.0) with a higher TBD graft density can yield exceptional results, even surpassing 96 %, in a mere 30 min at a mild temperature 30 °C when utilizing water as a green and easily available solvent. Furthermore, the catalyst can be effortlessly isolated from the reaction system and displays notable reusability for a minimum of 10 cycles without show obvious decline in performance.
A one-pot, sequential, three-component procedure is reported for the synthesis of poly-substituted dihydropyridines via the condensation reaction of diamines or aminophenoles, 1,1-bismethylmethio-2-nitroethylene and α,β-unsaturated aromatic ketones in acetonitrile under reflux conditions. A range of fused and non-fused poly-substituted dihydropyridines were prepared in good to high yields with short reaction times.
The review is focused on C–C and C–heteroatom bond forming methodologies involving reactions arising after hydropalladation of alkynes and allenes using Pd0 catalysts associated to catalytic or stoichiometric amounts of carboxylic acids. Most of the procedures occur with complete or high atom-economy, avoiding large generation of waste and producing functionalized compounds. The synthetic scope is presented and mechanistic problems are discussed.
The monofluoroalkenes are found widespread applications in areas such as bioactive molecules, materials science and synthetic organic chemistry, therefore, investigating efficient methodologies to construct monofluoroalkenes is still in demand. In this paper, we reported an efficient synthesis of monofluoroalkenyl substituted pyranones/pyridones by using the gem-difluorocyclopropanes (gem-DFCPs) as monofluoroalkenyl precursors. In the presence of Palladium catalyst, the monofluoroalkenyl group was introduced into the C3 positions of pyranones/pyridones successfully. The reaction was featured with high regioselectivity, mild conditions, broad substrate scope, easy to scale up synthesis, which provided a novel avenue for the late-stagy modification of pyranones/pyridones.
A commercially available nickel was utilized as an effective catalyst for the exclusive hydrogenation of nitroarenes to primary anilines in gram-scale without additional column chromatographic purification. This novel synthetic hydrogenation strategy features wide substrate scope, mild conditions and operational simplicity in aqueous media at room temperature. Further transformations resulted in the delivery of important amine-containing drugs and pharmaceutical intermediates.