Enrico Mincione

Selective oxidation of phenol and anisole derivatives to quinones with hydrogen peroxide and polymer-supported methylrhenium trioxide systems

Abstract A convenient and efficient application of heterogeneous poly(4-vinylpyridine)/methyl rhenium trioxide (PVP/MTO) systems for the selective oxidation of substituted phenol and anisole derivatives to benzoquinones is described. Environment friendly, easily available, and low cost H 2 O 2 was used as the oxygen atom donor. All catalysts were stable systems for at least five recycling experiments. In the oxidation of some natural phenols such as cardanol derivatives higher conversion and yields of benzoquinones were observed with respect to MTO in homogeneous phase suggesting a support-mediated molecular recognition process based on hydrogen-bonding interactions.

Convenient synthesis of hydroxytyrosol and its lipophilic derivatives from tyrosol or homovanillyl alcohol.

Hydroxytyrosol, a naturally occurred o-phenolic compound exhibiting antioxidant properties, was synthesized by a three-step high-yielding procedure from natural and low-cost compounds such as tyrosol or homovanillyl alcohol. First, the efficient chemoselective protection of the alcoholic group of these compounds was performed by using dimethyl carbonate (DMC) as reagent/solvent; second, the oxidation with 2-iodoxybenzoic acid (IBX) or Dess-Martin periodinane reagent (DMP) and in situ reduction with sodium dithionite (Na2S2O4) allowed the preparation of carboxymethylated hydroxytyrosol; finally, by a mild hydrolytic step, hydroxytyrosol was obtained in high yield and purity, as confirmed by NMR spectra and HPLC profile. By using a similar methodology, lipophilic hydroxytyrosol derivatives, utilized as additives in pharmaceutical, food, and cosmetic preparations, were prepared. In fact, at first the chemoselective protection of the alcoholic group of tyrosol and homovanillyl alcohol was performed by using acyl chlorides without any catalyst to obtain the corresponding lipophilic derivatives, and then these compounds were converted in good yield and high purity into the hydroxytyrosol derivatives by oxidative/reductive pathway with IBX or DMP and Na2S2O4.

Conversion of naringenin and hesperetin by heterogeneous catalytic Baeyer-Villiger reaction into lactones exhibiting apoptotic activity

Naringenin and hesperetin were converted into the corresponding lactones by hydrogen peroxide activated by poly(4-vinylpiridine)-supported methyltrioxorhenium in t-butanol, an environmentally friendly catalytic system. The products showed a marked apoptotic activity in the genetic tests.

Selective epoxidation of monoterpenes with H2O2 and polymer-supported methylrheniumtrioxide systems

Abstract A convenient and efficient synthesis of monoterpene epoxides by application of heterogeneous poly(4-vinylpyridine)/methyl rhenium trioxide (PVP/MTO) and polystyrene/methyl rhenium trioxide (PS/MTO) systems is described. Even highly sensitive terpenic epoxides were obtained in excellent yield. Environment friendly, easily available, and low cost H 2 O 2 was used as oxidant. Catalysts were stable systems for at least five recycling experiments.

A new and efficient Baeyer–Villiger rearrangement of flavanone derivatives by the methyltrioxorhenium/H2O2 catalytic system

Abstract The catalytic Baeyer–Villiger rearrangement of flavanones is described by the use of the homogeneous methyltrioxorhenium (MTO)/H2O2 system. In these experimental conditions 3,4-dihydro-4-phenyl-1,5-benzodioxepin-2-ones and previously not reported para-quinone derivatives have been obtained in mild experimental conditions from acceptable to good yields.

Selective Oxidation of Uracil and Adenine Derivatives by the Catalytic System MeReO3/H2O2 and MeReO3/Urea Hydrogen Peroxide

Abstract Methyltrioxorhenium (MTO) is a useful and selective catalyst for the oxidation of uracil and purine derivatives using environmentally friendly hydrogen peroxide (H 2 O 2 , 30% water solution) or hydrogen peroxide/urea adduct (UHP) as oxygen atom donors. In particular, the MTO/UHP system constitutes a convenient combination to convert uracil derivatives into the biologically relevant 5,6-oxiranyl-5,6-dihydrouracils in good yields. Purine derivatives are selectively oxidized to the corresponding 1-oxides, the best yield being obtained in the presence of pyrazine-2-carboxylic acid (PCA). The oxidation of the plasmid pBG1 is also reported as the first example of double-strand DNA cleavage mediated by the catalytic system MTO/H 2 O 2 .

Oxyfunctionalization of steroids by dioxiranes: Site and stereoselective C14 and C17 hydroxylation of pregnane and androstane steroids.

Dimethyldioxirane showed to be site and stereoselective in the CH oxygen insertion at C14 and C17 positions of pregnane and androstane steroids. Fine steric control and evidence for the influence of the carbonyl group on the dioxirane reactivity are reported.

Selective oxidation of diols by H2O2/TS-1 system and by DMDO

Abstract Selective oxidations of secondary hydroxyl groups vs. primary ones in 1,n-diols by TS-1/H2O2 catalitic system and by dimethyldioxirane, new reagents with low environmental pollution, are reported.

Improved Conversion of Vitamin D2 into the Windaus Ketone and Its Regioselective Hydroxylation Via Organoboranes at C26

Abstract The improved oxidative conversion of Vitamin D2 into the Windaus ketone as well as the regioselective hydroxylation via organoboranes at C26 of the title ketone is reported.

Efficient desymmetrization of 1,2 and 1,3 diols by dimethyldioxirane

Abstract Dimethyldioxirane was used to monooxidize 1,2 and 1,3 sec,sec-diols to the corresponding ketoalcohols, exploiting the inhibiting effect of the formed carbonyl group on the course of the process.