Synthesis and Characterization of Bimetallic Nanoclusters Stabilized by Chiral and Achiral Polyvinylpyrrolidinones. Catalytic C(sp)-H Oxidation.

Second-generation chiral-substituted poly--vinylpyrrolidinones (CSPVPs) (-)- and (+)- were synthesized by free-radical polymerization of (3a,6a)- and (3a,6a)-5-ethenyl-tetrahydro-2,2-dimethyl-4-1,3-dioxolo[4,5-]pyrrol-4-one, respectively, using thermal and photochemical reactions. They were produced from respective -isoascorbic acid and d-ribose. In addition, chiral polymer (-)- was also synthesized from the polymerization of ()-3-(methoxymethoxy)-1-vinylpyrrolidin-2-one. Molecular weights of these chiral polymers were measured using HRMS, and the polymer chain tacticity was studied using C NMR spectroscopy. Chiral polymers (-)-, (+)-, and (-)- along with poly--vinylpyrrolidinone (PVP, MW 40K) were separately used in the stabilization of Cu/Au or Pd/Au nanoclusters. CD spectra of the bimetallic nanoclusters stabilized by (-)- and (+)- showed close to mirror-imaged CD absorption bands at wavelengths 200-300 nm, revealing that bimetallic nanoclusters' chiroptical responses are derived from chiral polymer-encapsulated nanomaterials. Chemo-, regio-, and stereo-selectivity was found in the catalytic C-H group oxidation reactions of complex bioactive natural products, such as ambroxide, menthofuran, boldine, estrone, dehydroabietylamine, 9-allogibberic acid, and sclareolide, and substituted adamantane molecules, when catalyst Cu/Au (3:1) or Pd/Au (3:1) stabilized by CSPVPs or PVP and oxidant HO or -BuOOH were applied. Oxidation of (+)-boldine -oxide using NMO as an oxidant yielded 4,5-dehydroboldine , and oxidation of (-)-9-allogibberic acid yielded C6,15 lactone and C6-ketone .