Fig. 9. Catalytic performance of the HybPyr material for four consecutive runs for the addition of propanal to β-nitrostyrene (β-nitrostyrene (0,1 mmol), aldehyde (1 mmol), 10 mol% 4-nitrophenol, 1 mL of DCM and 20 mol% HybPyr), 8–10 h. Selectivity towards Michael adducts was >99%.