Dino Gnecco

1) H and (13) C NMR characterization of new cycloartane triterpenes from Mangifera indica.

From the stem bark of Mangifera indica, seven cycloartane‐type secondary metabolites were isolated. Compound 1 has been isolated for the first time from M. indica, whereas compounds 2 (2a and 2b, as an epimeric mixture), 3, and 4 are new triterpenoid‐type cycloartanes. Unambiguous 13C and 1H NMR assignments for these compounds and the known compounds mangiferonic acid (compound 5), isomangiferolic acid (compound 6), ambolic acid (compound 7), and friedelin (compound 8) are reported; the latter because full NMR data for these compounds are not available in the literature. Copyright

Oxidation of chiral non-racemic pyridinium salts to enantiopure 2-pyridone and 3-alkyl-2-pyridones

Abstract Oxidation of chiral non-racemic pyridinium salt 1a and 3-alkyl pyridinium salts 1b and 1c with potassium ferricyanide in an alkaline medium provides a short and practical access to enantiomerically pure 2-pyridone ( 2a ) and 3-alkyl-2-pyridones ( 2b and 2c ) in high yields and very good regioselectivity from derivatives 1 ( b – c ).

New methodology for the synthesis of enantiopure (3R,2aR)-(−)-3-phenyl-hexahydro-oxazolo[3,2-a]-pyridin-5-one: a synthesis of (S)-(+)-coniine

Abstract A new and efficient methodology for the enantiopure synthesis of (3R,2aR)-(−)-3-phenyl-hexahydro-oxazolo[3,2-a]pyridin-5-one 3 starting from (1′R)-(−)-1-(2′-hydroxy-1′-phenyl-ethyl)-(1H)-pyridin-2-one 1 is described. In addition, the enantiospecific synthesis of (S)-(+)-coniine hydrochloride 6 in good yield from 3 is reported.

Synthesis of (2R,3S)-( -)-2-phenyl-3-methylaziridine

Abstract We report the total synthesis of aziridine 3 , carried out in a two-step method involving double Walden inversion at the carbon atom bearing the hydroxy group of (1 R ,2 S )-(−)-norephedrine, 1 , which was used as starting material. Compound 3 was obtained for the first time as a solid therefore allowing its unambiguous X-ray structure determination.

A SHORT ENANTIOSELECTIVE ACCESS TO 2,3,6-TRIALKYLPIPERIDINES AND 5,8-DIALKYLINDOLIZIDINES

Abstract An enantioselective access to 2,3,6-trialkylpiperidines 5 is described. This sequence is illustrated by the four-step syntheses, from salts 1, of piperidine 6 and indolizidines 7 and 8. The overall yields are in the range 10–15%. The stereochemistry of intermediates is discussed, supported by two X-ray studies, and comparison with analogs. Stereochemical properties of intermediate oxazolidine derivatives 4 were used to orient the syntheses towards different diastereoisomers such as 7 or 8.

Synthesis and Structure of New Heterocyclic Derivatives of Curcumin

New heterocyclic derivatives of curcumin (3) of different ring size were synthesized by reaction of a key intermediate, 1,7-bis(4-acetoxy-3-methoxyphenyl)hepta-3,5-dione (5) with some bi-nucleophilic molecules. These new synthetic derivatives were obtained in good yields and the structure of all compounds was supported by MS, IR, ID and 2D 1 H and 1 3 C NMR spectra and elemental analysis.

A SHORT SYNTHESIS OF INDOLIZIDINE (+)-209B FROM (3R,6S,8aS)-(-)-6-METHYL-3-PHENYLHEXAHYDROOXAZOLO[3,2-a]-PYRIDIN-5-ONE

The synthetic potential of enantiopure (3R,6S,8aS)-(-)-6-methyl-3-phenylhexahydrooxazolo[3,2-a]pyridin-5-one 2 is illustrated by a short synthesis of the 5,8-disubstituted indolizidine alkaloid (+)-209B.

Synthesis and characterization of a new (phthalocyani-nato)bis(carboxylate) silicon(IV) compound with increased solubility

The synthesis and spectroscopic characterization of a new soluble silicon(IV) phthalocyanine complex is presented. The compound shows an increased solubility compared to its SiPcCl2 precursor and this allowed solution 1H NMR characterization. The assignment of the 1H NMR signals for the axial ligands is greatly facilitated due to the anisotropic high ring current effects from the macrocycle. In addition, good quality crystals were grown from this more soluble material for molecular structure determination by single-crystal X-ray diffraction analysis. The molecular structure determination shows that the complex crystallizes in a non-centrosymmetric space group due to the inherent chirality of the naproxene ligands. Bond lengths and angles fit well to other analogous compounds previously reported.

Curcuma treatment prevents cognitive deficit and alteration of neuronal morphology in the limbic system of aging rats

Curcuma is a natural compound that has shown neuroprotective properties, and has been reported to prevent aging and improve memory. While the mechanism(s) underlying these effects are unclear, they may be related to increases in neural plasticity. Morphological changes have been reported in neuronal dendrites in the limbic system in animals and elderly humans with cognitive impairment. In this regard, there is a need to use alternative therapies that delay the onset of morphologies and behavioral characteristics of aging. Therefore, the objective of this study was to evaluate the effect of curcuma on cognitive processes and dendritic morphology of neurons in the prefrontal cortex (PFC), the CA1 and CA3 regions of the dorsal hippocampus, the dentate gyrus, and the basolateral amygdala (BLA) of aged rats. 18‐month‐old rats were administered curcuma (100 mg/kg) daily for 60 days. After treatment, recognition memory was assessed using the novel object recognition test. Curcuma‐treated rats showed a significant increase in the exploration quotient. Dendritic morphology was assessed by Golgi–Cox staining and followed by Sholl analysis. Curcuma‐treated rats showed a significant increase in dendritic spine density and dendritic length in pyramidal neurons of the PFC, the CA1 and CA3, and the BLA. The preservation of dendritic morphology was positively correlated with cognitive improvements. Our results suggest that curcuma induces modification of dendritic morphology in the aforementioned regions. These changes may explain how curcuma slows the aging process that has already begun in these animals, preventing deterioration in neuronal morphology of the limbic system and recognition memory.

The Zincke's Reaction: A New Alternative for the Preparation of L-[2-(3-Indol)Ethyl]-Alkylpyridinium Chloride Derivatives

Abstract The Zinckes salts 3 (a-f) were prepared and used for the synthesis of 1-[(2-(3-indol)-ethyl]alkylpyridinium chloride derivatives 5 (a-f) in high yields.