: While historically significant, newer research often favors alternative pathways, such as direct hydride transfer (Scheme 2D), because certain experimental observations—like the lack of a detectable covalent intermediate in all cases—make the nucleophilic path harder to verify. 2. Nickel-Catalyzed Chemical Synthesis
: In this model, the amino group of the substrate (like dopamine or serotonin) attacks the C4a position of the flavin cofactor to form a covalent intermediate. Scheme 2C
: This method is praised for being low-cost and environmentally friendly, though the effectiveness depends heavily on the surface properties of the nanoparticle and the solvent used. : While historically significant