Heterogeneous fiber-based asymmetric quinine catalyst for highly enantioselective Michael addition and tandem cyclization to 4H-pyrans.

• Prepare a novel quinine functionalized fiber (PAN QN F) used to asymmetric reaction. • The PAN QN F possess high catalytic activity, enantioselectivity and recyclability. • Asymmetric Michael addition is catalyzed excellently by PAN QN F with ee up to greater than 99%. • (S)-2-amino-4H-pyran derivatives are prepared by PAN QN F with ee greater than 99%. As a new type of catalyst support, polyacrylonitrile fiber (PANF) has diverse advantages in physical and chemical properties. Quinine and its derivatives have been widely used as asymmetric organocatalysts recently. By combining the advantages of PANF and quinine, a novel fiber-based asymmetric catalyst (PAN QN F) was successfully prepared through thiol-ene click reaction and characterized by FTIR, XRD, EA, SEM, TGA and mechanical strength analysis. The PAN QN F exhibited excellent catalytic performance for asymmetric Michael addition of malononitrile to chalcone with ee up to > 99%. Further research revealed that the (S)-2-amino-4 H -pyran derivatives were also successfully prepared using PAN QN F as a catalyst in asymmetric tandem Michael addition-nucleophilic annulation of α -phenylchalcone and malononitrile, and the ee of the tandem reaction can also reach greater than 99%. In addition, as an immobilized catalyst, PAN QN F showed relatively wide temperature tolerance and good recycling performance. Overall, the fiber catalyst has the advantages of easy preparation, high activity, high enantioselectivity, wide reaction temperature range, simple separation and good recyclability, which exhibits great potential for industrial application. [ABSTRACT FROM AUTHOR]