Halogenation functional mimics

Initial studies on functional mimics of V-BrPO were driven by the lack of spectroscopic techniques capable of observation of the vanadium(V) site in the enzyme. Early on it was found that acidic solutions of cw-dioxovanadium(V) (cis-V02+) catalyzed the oxidation of halides by dihydrogen peroxide, resulting in halogenation of an organic substrate and halide-assisted disproportionation of dihydrogen peroxide [73],... 

The halogen end group can be transformed into other functionalities by means of standard organic procedures, such as a nucleophilic displacement reaction. Different authors have investigated this process of the nucleophilic displacement reactions with model compounds, to confirm the feasibility and selectivity. Compounds such as 1-phenylethyl halide, methyl 2-bromopropionate, and ethyl 2-bromoisobutane mimic the end groups of PSs, poly(alkyl acrylates), and poly(alkyl methacrylates), respectively. Different compounds have been tested, such as sodium azide, n-butylamine, and n-butylphosphine. 

Remote or Inactive Positions.—Breslow and his co-workers have sought to mimic some aspects of enzyme behaviour in other ways, and have published a full paper on remote halogenation of steroids, giving various partial syntheses [e.g. cortexolone (24) to dihydrocortisone (25)] they have extended the principle to remote epoxida-tion. The reiterative functionalization process of Watt has also been applied in the steroid field, providing activation at C-18, and aimed eventually at preparing aldosterone. 

Perez-Baena et al. reported SCNPs that contained a tris(penta-fluorophenyl)boron (B(C6F6)3) active site to mimic the function of reductase and polymerase. Catalysis with this SCNPs could only be carried out in halogenated solvents, toluene, and benzene. Solvents that could form adducts with boron were unsuitable, as they quenched the catalyst. The kinetics and TOP of catalysis by these particles were influenced by size, composition, quantity, and location of the active sites in the SCNPs. The TOP was also proportional to the molecular weight and inversely proportional to the hydrodynamic radius of the SCNPs. 

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