Piergiorgio Vergamini

Regioselective Synthesis of Natural and Unnatural (Z)-3-(1-Alkylidene)phthalides and 3-Substituted Isocoumarins Starting from Methyl 2-Hydroxybenzoates

Abstract ( Z )-3-(1-Alkylidene)phthalides and 3-substituted isocoumarins, which include compounds bearing a substituent on their benzene ring, have been selectively and efficiently synthesized by a new protocol which involves: (i) the conversion of methyl 2-hydroxybenzoates into the corresponding nonaflates; (ii) Pd-catalyzed alkynylation reactions of these derivatives; (iii) the conversion of the so obtained methyl 2-(1-alkynyl)benzoates into the corresponding carboxylic acids followed by a transition metal-catalyzed heteroannulation reaction. This procedure has been used to prepare either natural products such as senkyunolide B, senkyunolide C, 3-propylisocoumarin and artemidin, or the MEM-ether of senkyunolide E. The regioselectivity of the transition metal-catalyzed cyclization reactions of 2-(1-alkynyl)benzoic acids has proven to be affected either by the catalyst used or the type of 1-alkynyl group present in these carboxylic acids.

Studies on the transition metal catalyzed synthesis of variously substituted (E)-3-[1-(aryl)methylidene]- and (E)-3-(1-alkylidene)-3H-furan-2-ones

5-Aryl and 5-alkyl substituted (E)-3-[1-(aryl)methylidene]- and (E)-3-(1-alkylidene)-3H-furan-2-ones, (E)-9, have been selectively synthesized by cyclization of the corresponding (E)-2-(1-alkynyl)-3-aryl/alkylpropenoic acids, (E)-11, in the presence of AgNO3 or Pd-catalysts such as trans-di(μ-acetato)bis[(di-o-tolylphosphino)benzyl]dipalladium(II) or that constituted of a mixture of Et3N and PdCl2(PhCN)2 or PdCl2(CH3CN)2. in a 3 : 1 molar ratio, respectively. A representative (E)-5-aryl-3-[1-(aryl)methylidene]-3H-furan-2-one, i.e. (E)-9i, has been also prepared by a tandem process involving a Pd(O)- and Cu(I)-catalyzed cross-coupling reaction between an 1-alkyne and a (Z)-3-aryl-2-bromopropenoic acid followed by a catalytic intramolecular oxypalladation of the resulting cross-coupled product. However, when this same approach was used to prepare an (E)-5-alkyl-3-[1-(aryl)methylidene]-3H-furan-2-one, i.e. (E)-9j, a mixture of (E)-9j and the corresponding (E)(Z)-5-(1-alkylidene)-3-(aryl)methyl-5H-furan-2-one, i.e. (E)(Z)-20, was obtained. Finally, in an attempt to prepare an (E)-4-alkyl-5-aryl-3-[1-(aryl)methylidene]-3H-furan-2-one, i.e. (E)-14a, by a tandem process involving the intramolecular oxypalladation of an (E)-enynoic acid, (E)-11, followed by a cross-coupling reaction of the resulting compound with an aryl iodide, a (Z)-5-(1-alkynyl)-4-aryl-3-arylmethyl-5H-furan-2-one, i.e. (Z)-22, has been stereoselectively obtained.

A New Approach to the Study of Human Solid Tumor Cells by Means of FT-IR Microspectroscopy

Cells coming from normal and neoplastic human lung tissue were analyzed by means of FT-IR microspectroscopy. Among the various methods tested to isolate the cells, mechanical treatment alone was found to yield the best results. Monolayers of cells were homogeneously distributed by cytocentrifuge preparation on BaF2 windows, and several spectra were obtained for different circular micro-areas of the order of one hundred microns in diameter. This procedure made it possible to obtain reliable spectra and to reject those containing additional bands due to impurities arising from the isolation treatment. Spectral differences between normal and neoplastic cells reflect an increase in the intensity of the bands corresponding mainly to PO2− symmetrical and asymmetrical vibrations of DNA in pathological samples with respect to normal ones. The value of the ratio of the integrated areas of the bands at 1080 and 1540 cm−1 due to DNA and proteins, respectively, makes it possible to differentiate between normal and abnormal cells, thus suggesting the use of this parameter as an original approach in the recognition of early neoplastic transformation undetectable by means of traditional procedures.

FT-IR investigation of the structural changes of Sulcis and South Africa coals under progressive heating in vacuum

Two samples of coals coming from South Africa and Sulcis (Sardinia, Italy) were subjected to progressive heating up to 800°C in vacuum. The infrared (IR) spectra of the residuals obtained at 100°C intervals from room temperature to 800°C show spectral changes ascribed to transformations at the level of the organic and inorganic components. Comparing these results with those previously obtained by heating the same coals in the presence of air and examining their pyridinic extracts, it appears that the Sulcis coal with respect to the other coals contains a lower amount of clay-minerals. Furthermore, the IR analysis shows that this coal is nearer to being a lignite than a hard-coal.

New possibilities of research in chronic lymphatic leukemia by means of fourier transform-infrared spectroscopy-II

Ten samples of lymphocytes coming from patients affected by chronic lymphatic leukemia and ten samples from normal subjects were studied by FT-IR spectroscopy. Spectral differences observed between the two kinds of cells correspond to an increase of the intensities, in the leukemic samples with respect to the normal ones, of the bands corresponding mainly to PO2- symmetrical and asymmetrical stretching vibrations of DNA. The ratios of the integrated areas of the band at 1080 cm-1 mainly involving the symmetrical stretching vibration of the O-P-O linkages of DNA, and of the band at 1540 cm-1, due to the proteic components of the lymphocytes, assume different values for the two kinds of cells. These ratios can constitute an additional marker to diagnose chronic lymphatic leukemia and may be usefully employed to evidence the early phases of the disease.

Analytical infrared spectral differences between human normal and leukaemic cells (CLL) — I

Two series of normal and leukaemic lymphocytes were examined by infrared spectroscopy in order to try to find spectral differences connected with chemical and biological modifications. The bands at 965 and 530 cm-1 present only in the spectra of leukaemic lymphocytes, assume particular significance. The C-H stretching region furnishes useful indications about the different ratios of the methyl groups compared with the methylene ones in the two cases. The infrared bands characteristic of the leukaemic lymphocytes seem to be due to chemical modifications not involving the DNA chain.

FTIR-microspectroscopy and DSC studies of poly(vinylidene fluoride)

Poly(vinylidene fluoride) (PVDF) samples, obtained by casting from tetrahydrofuran solutions and submitted to various thermal treatments, have been examined by Fourier transform-infrared microspectroscopy (FTIR-M) and differential scanning calorimetry (DSC). This kind of analysis allowed us to examine microdomains of samples with different morphological characteristics and to obtain an indication of the polymorphism of PVDF. In some cases the simultaneous presence of two or three forms has been evidenced thanks to the comparison of FTIR-M spectra and DSC traces. Vibrational spectra of single crystalline forms can be recorded by FTIR-M on phase homogeneous microdomains.

Synthesis of vinyl nonaflates derived from β-ketoesters, β-diketones or α-diketones and their palladium-catalyzed cross-coupling reactions with organozinc halides

Abstract Cyclic and acyclic β-ketoesters 4 , a typical cyclic α-diketone 5 and a typical cyclic β-diketone 6 were converted to the corresponding vinyl nonaflates of general formula 7, 8 and 9 , respectively, by reaction with 1.2–1.5 equiv of NaH in DMF at 20–55 °C followed by treatment with 1.15–1.30 equiv of perfluoro-1-butanesulfonyl fluoride at 20 °C. These vinyl nonaflates, which were purified by MPLC on silica gel, proved to be excellent electrophiles in Pd-catalyzed cross-coupling reactions with aryl-, 1-alkynyl- and alkylzinc chlorides. A variety of cyclic and acyclic tetrasubstituted α,β-unsaturated esters which included stereoisomerically pure compounds, a 2-substituted 3-aryl-2-cyclopentenone and naturally-occurring dihydrojasmone were cleanly synthesized by these smooth and selective cross-coupling reactions.

Infrared Characterization of Nuclei Isolated from Normal and Leukemic (B-CLL) Lymphocytes: Part III

Nuclei extracted from lymphocytes coming from normal subjects and from patients affected by chronic lymphatic leukemia (B-CLL) were studied by means of infrared spectroscopy. Substantial spectral differences were found above all in the region of the phosphate-group vibrations of DNA. The ratios of the integrated areas of the bands at 1080 and 1540 cm−1, due to the symmetrical stretching vibrations of PO2− groups and to proteic components, respectively, assume increasing values, which are localized in quite separate ranges, for normal lymphocytes, leukemic lymphocytes, normal nuclei, and leukemic nuclei. These values, indicating a different distribution of DNA and of proteic components between normal and leukemic cells and between normal and leukemic nuclei, may assume a remarkable significance in the precocious diagnosis of leukemia (B-CLL) and in following the course of the disease. In the case of leukemic nuclei, the ratio, in weight, of the two components reaches the value of 1:1.

FTIR microspectroscopy and DSC analysis of blends of poly(vinylidene fluoride) with isotactic and syndiotactic poly(methyl methacrylate)

Films of blends of poly(vinylidene fluoride) (PVDF) with isotactic and syndiotactic poly(methyl methacrylate) (i-PMMA and s-PMMA), obtained by casting tetrahydrofuran (THF) and dimethyl sulphoxide (DMSO) solutions onto BaF2 windows, have been investigated by means of FTIR-microspectroscopy (FTIR-M), optical microscopy and differential scanning calorimetry (DSC). The study of the effect of the PMMA tacticity on the intermolecular interaction between the two components, as well as on the structure, morphology and thermal behaviour of these blends, is the object of this paper. On the basis of the major shift of the carbonyl band of i-PMMA in the mixtures, the occurrence of stronger interactions for PVDF/i-PMMA compared with PVDF/s-PMMA blends can be suggested.