Kiroptikai spektroszkópia alkalmazása a szerves vegyületek szerkezetvizsgálatában = Application of chiroptical spectroscopy in the structural analysis of organic compounds

Az ifjúsági OTKA pályázat keretében elért eredmények az alábbi három fő témakör köré csoportosíthatók: I) O-heterociklusok és szénhidrát származékok enantioszelektív szintézise és sztereo-kémiájuk vizsgálata kiroptikai spektroszkópiával. Ezen belül az alábbi vegyületeket vizsgáltuk: 1) cis és trans-pterokarpánok 2) dioxán típusú (2-naftil)metil acetál védőcsoportokat tartalmazó glükozidok és galaktozidok 3) S-S vagy Se-Se kötést tartalmazó dikalkogenid-diszacharidok 4) Silybum marianum L. flavanolignán komponensei 5) szintetikus optikailag aktív 1,4-benzodioxánok 6) izopropilidén guanozin telekelikus dimerje 7) szubszituált 4H-benzopirán (kromán) és 2,3-dihidroizokumarin származékok II) Izolált és szintetikus flavonoid származékok abszolút konfigurációjának meghatározása online HPLC-CD technikával. Az alábbi vegyületcsoportokat vizsgáltuk: 1) izolált 2,8?-biflavanoid izomerek 2) szintetikus eritro és treo-8.4?-oxineolignének 3) izolált 2-metilkromanon származékok III) Izolált természetes anyagok abszolút konfigurációjának meghatározására egy új szilárd fázisú TDDFT/CD módszert vezettünk be. Az alábbi természetes anyagok abszolút konfigurációját határoztuk meg: 1) plumericin és isoplumericin 2) xyloketal F 3) phomoxanthone A 4) globusoxanthone A 5) ascochin 6) massarilactone E 7) tetrahidropyrenophorol 8) hypothemycin 9) palmarumycin és papyracillic sav A kutatás eredményeként 23 angol nyelvű folyóiratcikket publikáltunk, egy cikket közlésre fogadtak el és egyet közlésre nyújtottunk be. | The scientific results achieved in the frame of the young scientist OTKA grant can be grouped around the following three major topics: I) Enantioselective synthesis of O-heterocycles and carbohydrates and the study of their stereochemistry by chiroptical spectroscopy. In this topic, the following compounds were investigated: 1) cis- and trans-pterocarpans 2) glycosides and galactosides containing dioxane-type (2-naphthyl)methyl acetal protecting groups 3) dichalcogenide disaccharides containing S-S or Se-Se bonds 4) flavanolignan constituents of Silybum marianum L. 5) synthetic optically active 1,4-benzodioxanes 6) telechelic dimmer of isopropylidene guanosine 7) substituted 4H-benzopyran (chromane) and 2,3-dihydroisocoumarine derivatives II) Configurational assignment of isolated and synthetic flavonoid derivatives by online HPLC-CD technique. The following types of compounds were studied: 1) isolated 2,8?-biflavanoid isomers 2) synthetic erithro- and treo-8.4?-oxyneolignenes 3) isolated 2-methylchromanone derivatives II) For the configurational assignment of isolated natural products, a novel solid-state TDDFT/CD method was introduced. The absolute configuration of the following natural products were deduced: 1) plumericin and isoplumericin 2) xyloketal F 3) phomoxanthone A 4) globusoxanthone A 5) ascochin 6) massarilactone E 7) tetrahydropyrenophorol 8) hypothemycin 9) palmarumycin and papyracillic acid As a result of the research, 23 scientific English journal articles were published, one paper has been accepted for publication and one has just been submitted

New 2-Methoxy Acetylenic Acids and Pyrazole Alkaloids from the Marine Sponge Cinachyrella sp.

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TDDFT-ECD and DFT-NMR studies of thaigranatins A–E and granatumin L isolated from Xylocarpus granatum

TDDFT-ECD calculations were utilized to explain the mirror image or different ECD spectra of previously reported homochiral natural products thaigranatins A–E and granatumin L, the simple comparison of which would result in a wrong stereochemical conclusion. The configurational assignment was confirmed independently and geometrical parameters of the chromophores governing the ECD spectra were identified in the structurally related natural products by analyzing the ECD spectra and geometries of the low-energy computed conformers obtained by different methods. Different conformations of the furan-2-yl-d-lactone subunit were found responsible for the mirror image ECD spectra of the homochiral thaigranatins C–E. Two DFT 13C NMR chemical shift calculation methods and DP4+ analysis were performed on the C-6 epimers of thaigranatin D, which together with the ECD calculation, could determine the absolute configuration of C-6 as (R)

Glucopyranosylidene-Spiro-Thiazolinones: Synthetic Studies and Determination of Absolute Configuration by TDDFT-ECD Calculations

Reactions of O-peracylated C-(1-bromo-β-d-glucopyranosyl)formamides with thioamides furnished the corresponding glucopyranosylidene-spiro-thiazolin-4-one. While O-debenzoylations under a variety of conditions resulted in decomposition, during O-deacetylations the addition of MeOH to the thiazolinone moiety was observed, and with EtOH and water similar adducts were isolated or detected. The structure and stereochemistry of the new compounds were established by means of NMR and electronic circular dichroism (ECD) data supported by time-dependent density functional theory ECD (TDDFT-ECD) calculations. TDDFT-ECD calculations could efficiently distinguish the proposed epimeric products having different absolute configuration in the spiro heterocyclic ring

Varioloid A, a new indolyl-6,10b-dihydro-5aH-[1]benzofuro[2,3-b]indole derivative from the marine alga-derived endophytic fungus Paecilomyces varotii EN-291

A new indolyl-6,10b-dihydro-5aH-[1]benzofuro[2,3-b]indole derivative, varioloid A (1), was isolated from the marine alga-derived endophytic fungus Paecilomyces variotii EN-291. Its structure was elucidated on the basis of extensive analysis of 1D and 2D NMR data and the absolute configuration was determined by time-dependent density functional theory-electronic circular dichroism (TDDFT-ECD) calculations. A similar compound, whose planar structure was previously described but the relative and absolute configurations and 13C NMR data were not reported, was also identified and was tentatively named as varioloid B (2). Both compounds 1 and 2 exhibited cytotoxicity against A549, HCT116, and HepG2 cell lines, with IC50 values ranging from 2.6 to 8.2 µg/mL