RESUMEN
New chiral ligands could be obtained by introducing proline moieties and imidazoline moieties to binaphthyl skeletons. The chiral ligands exhibited balanced rigidity and flexibility which could allow the change of the conformations during the reactions on one hand, and could provide sufficient asymmetric induction on the other. The proline moiety could act as a linker connecting the binaphthyl skeletons and the imidazoline moieties as well as a coordinating group for the central metal, and the electronic and steric properties of the imidazoline groups could be carefully fine-tuned by the use of different substituents. In the presence of Cu(II) catalyst bearing such chiral ligands, aza-Friedel-Crafts reaction of 1-naphthols and electron-rich phenols with isatin-derived ketimines provided the desired products with good to excellent yields and up to 99 % ee. The reactions showed good scalability, and excellent ee could still be obtained when the reaction was carried out in gram-scale.
RESUMEN
This study collected data on waste generation and management in China between 1979 and 2020 from government statistics and literature and reviewed the development of municipal solid waste (MSW) management in China. The extended stochastic impact by regression on population, affluence and technology (STIRPAT) model was employed to identify the driving forces of MSW generation, and the cointegration analysis showed that economy (0.35, t = -3.47), industrial structure (3.34, t = -20.77) and urbanization (-1.5, t = 5.678) were the significant socioeconomic driving forces in the long run. By employing the framework of evolutionary economics, this study then investigated the internal rules of long-term interaction between socioeconomic factors and MSW management. The results indicate that, in the long run, MSW management development can be viewed as an evolutionary process that includes a continuous adaptation to external socioeconomic factors and the co-evolution of internal institutions and technologies. Adaptation and diversity of institutions and technologies play an important role in achieving sustainable waste management and circular economy (CE). This study offers a novel evolutionary perspective for explaining dynamic changes of MSW management in China, as well as recommendations for emerging economies to achieve sustainable waste management and CE goals.
RESUMEN
This paper describes the design and application of new binaphthyl-proline-based chiral ligands bearing imidazoline functional groups. These chiral ligands incorporate the advantages of both the binaphthyl and proline skeletons, they are featured with regulatable electronic and steric properties for the imidazoline functional groups, and form chiral complexes with different metal salts such as cuprous acetate. In the presence of an appropriate amount of a chiral catalyst, enantioselective conjugate addition of 4-hydroxycoumarin or related nucleophiles to different ß,γ-unsaturated α-ketoesters proceeded readily, giving the desired products in high yield (up to 99%) and excellent enantiomeric excess (up to 99%).
RESUMEN
The copper(II)-catalyzed enantioselective aza-Friedel-Crafts reaction of indoles with isatin-derived N-Boc-ketimines was developed by using tunable chiral O-N-N tridentate ligands derived from BINOL and proline. In general, the reaction afforded chiral 3-indolyl-3-aminooxindoles under mild conditions in high yields (83-97%) with excellent ee (69-99%).
RESUMEN
High yields (up to 96%) and high ee (up to 92%) were achieved for chiral copper(II) complex-catalysed enantioselective Michael addition of malonates to ß,γ-unsaturated-α-ketoesters. The chiral ligands took advantage of both the binaphthyl and the proline moieties, and substituents with different electronic and steric features could be tolerated. The reactions could be carried out under mild conditions, and a gram scale reaction could be realised without the loss of yield and enantioselectivity.
RESUMEN
Using binaphthyl-proline-based chiral ligands, Zn(II)-catalysed addition of alcohols and tert-butyl hydroperoxide to isatin-derived N-Boc ketimines provided the isatin-derived C3 N,O-aminals in up to 99% yield and up to 99% ee. The reactions could be carried out under mild conditions and a gram-scale reaction could be realized without the loss of the yield and enantioselectivity.