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71.
Summary Salts of the anions [SnX5]–, [SnX4Cl, [SnX3Cl2]–, [SnX3]–, [PbX3]–, [SbX4]–, [SbX3Cl]–, [SbX2Cl2]–, [BiX4]–, [AuCl2]–, [AuX2]–, [AuXCl]–, [AuX4]–, [Au2X6]2– and [PtX4]2–, where X– = C6F5S–, have been isolated and characterised. The neutral SbX3 and BiX3 species, have also been isolated and shown to be pyramidal monomers (19F.n.m.r., i.r., and Raman spectral evidence). Various physical properties of the complexes prepared, as well as their stereochemistries (where these could be ascertained), are similar to those of the known corresponding halogeno compounds of these elements. These results further demonstrate the pseudo-halide nature of the pentafluorothiophenoxide ion.Author to whom all correspondence should be directed at: Laboratoire de Chimie de Coordination, Uniyersité Louis Pasteur, 67008 Strasbourg, France. 相似文献
72.
Synthesis and Chirality of (5S,6R)-5,6-Epoxy-5,6-dihydro-β,β-carotene and (5R,6R)-5,6-Dihydro-β,β-carotene-5,6-diol, a Compound with Unexpected Solubility Characteristics Wittig-condensation of azafrinal ( 1e ) with the phosphorane derived from 7 leads to a (1:3)-mixture of (E)-9′- and (Z)-9′-β,β-carotene-diol 3 , from which pure and optically active 3 ((5R,6R)-5,6-dihydro-β,β-carotene-5,6-diol) has been isolated as bright violet leaflets, m.p. 168°. Due to the trans-configuration of the diol moiety and to severe steric hindrance, hydrogen bonding is reduced to such an extent, that 3 behaves much more as a hydrocarbon than as a diol. There is good evidence that the so-called ‘β-oxycarotin’ obtained by Kuhn & Brockmann [15] by chromic acid oxidation of β, β-carotene is the corresponding racemic cis-diol. 3 has been converted into (5S, 6R)-5,6-epoxy-5.6-dihydro-β,β-carotene ( 4 ), m.p. 156°. This transformation establishes for the first time the chirality of a caroteneepoxide (without other O-functions). Full spectral and chiroptical data including a complete assignement of 13C-chemical shifts for azafrin methyl ester and 3 are presented. 相似文献
73.
FlorianC. Stintzing Florian Kugler Reinhold Carle Jürgen Conrad 《Helvetica chimica acta》2006,89(5):1008-1016
Due to their inherent liability towards highly acidic conditions previously considered to be a prerequisite for data acquisition, betaxanthin structure dereplication by NMR spectroscopy has been scarcely reported and was, hitherto, exclusively based on 1H‐NMR data interpretation. Applying only slightly acidic conditions, we herein report the first 13C‐NMR data of two betaxanthins, i.e., indicaxanthin ( 1 ), isolated from yellow‐orange cactus pear fruits (Opuntia ficus‐indica [L.] Mill . cv. ‘Gialla’), and of miraxanthin V ( 2 ) from yellow Swiss chard petioles (Beta vulgaris L. ssp. cicla [L.] Alef . cv. ‘Bright Lights’), as derived by gHSQC‐ and gHMQC‐NMR experiments and inverse detection. 相似文献
74.
Murat Acemoglu Peter Uebelhart Max Rey Conrad Hans Eugster 《Helvetica chimica acta》1988,71(5):931-956
Syntheses of Enantiomerically Pure Violaxanthins and Related Compounds The epoxides 16 and ent- 16 , prepared by Sharpless-Katsuki oxidation of 15 in excellent yield and very high enantiomeric purity, were used as synthons for the preparation of (+)-(S)-didehydrovomifoliol (45) , (+)-(6S, 7E, 9E)-abscisic ester 46 , (+)-(6S, 7E, 9Z)-abscsic ester 47 , (?)-(3S, 7E, 9E)-xanthoxin (49) , (?)-(3R, 7E, 9E)-xanthoxin (50) , (3S, 5R, 6S, 3′S,5′R, 6′S, all-E)-violaxanthin (1) (3R, 5R,6S,3′R,5′R,6′S, all-E)-violaxanthin (55) and their (9Z) (see 53 , 57 ), (13Z) (see 54 , 58 ), and (15Z) (see 60 ) isomers. The novel violadione ( 61 ) was prepared from 1 by oxidation with DMSO/Ac2O. By base treatment, 61 was converted into violadienedione (62) , a potential precursor of carotenoids with phenolic end groups. 相似文献
75.
Seturam Bandacharaya Katti Peter Rüedi Conrad Hans Eugster 《Helvetica chimica acta》1982,65(7):2189-2197
Diterpenoids from Leaf Glands of Plectranthus purpuratus: p-Quinomethanes, Extended Quinones, p-Acylcatechols and a Novel Phyllocladanon Derivative From the complex mixture of terpenoids from the title plant, the following novel diterpenoids have been isolated: 11-hydroxy-19-(3-methyl-2-butenoyloxy)- and 11-hydroxy-19-(3-methylbutanoyloxy)-5,7,9 (11), 13-abietatetraen-12-one ( 1a / 1b ), 11-hydroxy-19-(3-methyl-2-butenoyloxy)- and 11-hydroxy-19-(3-methylbutanoyl-oxy)-7,9(11), 13-abietatrien-6,12-dione ( 2a / 2b ), 6α, 11-dihydroxy-19-(3-methyl-2-butenoyloxy)- and 6α, 11 -dihydroxy-19-(3-methylbutanoyloxy)-7,9 (11), 13-abieta-trien-12-one ( 3a / 3b ), 11,12-dihydroxy-19-(3-methyl-2-butenoyloxy)- and 11,12-di-hydroxy-19-(3-methylbutanoyloxy)-8,11,13-abietatrien-7-one ( 4a / 4b ), and (16R)-17,19-diacetoxy-16-hydroxy-13β-kauran-3-one (=(16R)-17,19-diacetoxy-16-hydro-xyphyllocladan-3-one; 10 ). Compounds 2 and 3 are derivates of taxodione and taxodone, respectively, 4 is a derivative of cryptojaponol. The structure of 10 is Wised on a single-crystal- X -ray analysis and CD . data. 相似文献
76.
( all-E)-12′-Apozeanthinol, Persicaxanthine, and Persicachromes Reexamination of the so-called ‘persicaxanthins’ and ‘persicachromes’, the fluorescent and polar C25-apocarotenols from the flesh of cling peaches, led to the identification of the following components: (3R)-12′-apo-β-carotene-3,12′-diol ( 3 ), (3S,5R,8R, all-E)- and (3S,5R,8S,all-E)-5,8-epoxy-5,8-dihydro-12′-apo-β-carotene-3,12′-diols (4 and 5, resp.), (3S,5R,6S,all-E)-5,6-epoxy-5,6-dihydro-l2′-apo-β-carotene-3,12′-diol =persicaxanthin; ( 6 ), (3S,5R,6S,9Z,13′Z)-5,6-dihydro-12′apo-β-carotene-3,12′-diol ( 7 ; probable structure), (3S,5R,6S,15Z)-5,6-epoxy-5,6-dihydro-12′-apo-β-carotene-3,12′-diol ( 8 ), and (3S,5R,6S,13Z)-5,6-epoxy-5,6-dihydro-12′-apo-β-carotene-3,12′-diol ( 9 ). The (Z)-isomers 7 – 9 are very labile and, after HPLC separation, isomerized predominantly to the (all-E)-isomer 6 . 相似文献
77.
Edith Mrki-Fischer Urs Marti Richard Buchecker Conrad Hans Eugster 《Helvetica chimica acta》1983,66(2):494-513
Carotenoids from Hips of Rosa pomifera: Discovery of (5Z)-Neurosporene; Synthesis of (3R, 15Z)-Rubixanthin Extensive chromatographic separations of the mixture of carotenoids from ripe hips of R. pomifera have led to the identification of 43 individual compounds, namely (Scheme 2): (15 Z)-phytoene (1) , (15 Z)-phytofluene (2) , all-(E)-phytofluene (2a) , ξ-carotene (3) , two mono-(Z)-ξ-carotenes ( 3a and 3b ), (6 R)-?, ψ-carotene (4) , a mono-(Z)-?, ψ-carotene (4a) , β, ψ-carotene (5) , a mono-(Z)-β, ψ-carotene (5a) , neurosporene (6) , (5 Z)-neurosporene (6a) , a mono-(Z)-neurosporene (6b) , lycopene (7) , five (Z)-lycopenes (7a–7e) , β, β-carotene (8) , two mono-(Z)-β, β-carotenes (probably (9 Z)-β, β-carotene (8a) and (13 Z)-β, β-carotene (8b) ), β-cryptoxanthin (9) , three (Z)-β-cryptoxanthins (9a–9c) , rubixanthin (10) , (5′ Z)-rubixanthin (=gazaniaxanthin; 10a ), (9′ Z)-rubixanthin (10b) , (13′ Z)- and (13 Z)-rubixanthin (10c and 10d , resp.), (5′ Z, 13′ Z)- or (5′ Z, 13 Z)-rubixanthin (10e) , lutein (11) , zeaxanthin (12) , (13 Z)-zeaxanthin (12b) , a mono-(Z)-zeaxanthin (probably (9 Z)-zeaxanthin (12a) ), (8 R)-mutatoxanthin (13) , (8 S)-mutatoxanthin (14) , neoxanthin (15) , (8′ R)-neochrome (16) , (8′ S)-neochrome (17) , a tetrahydroxycarotenoid (18?) , a tetrahydroxy-epoxy-carotenoid (19?) , and a trihydroxycarotenoid of unknown structure. Rubixanthin (10) and (5′ Z)-rubixanthin (10a) can easily be distinguished by HPLC. separation and CD. spectra at low temperature. The synthesis of (3 R, 15 Z)-rubixanthin (29) is described. The isolation of (5 Z)-neurosporene (6a) supports the hypothesis that the ?-end group arises by enzymatic cyclization of precursors having a (5 Z)- or (5′ Z)-configuration. 相似文献
78.
Coleons C, D, I, I′, obtained from a Madagascan Plectranthus sp. nov.. Interconversion of cis- and trans-A/B-6,7-Diketoditerpenes. Fairly large amounts of Coleons C and D, as well as Coleons I and I′ (3-O-formyl derivative of Coleon I) can bc isolated from the orange glands of an unclassified North Madagascan Plectranthus sp. A reversible transformation of cis- and trans-A/B-6,7-dioxo-abietane via its diosphenol has been achieved for the first time. CD.-Spectra of these compounds are presented. Hydrogenolysis of Coleon D leads to 6β,16-dihydroxy-royleanone. 相似文献
79.
Partial Synthesis of Grandidones A, 7-Epi-A, B, 7-Epi-B, C, D and 7-Epi-D, from 14-Hydroxytaxodione Oxydative addition of coleon U ( 6 ) to 14-hydroxytaxodione ( 5 ) in the presence of Fétizon's reagent mainly leads to grandidone A ( 1a ) and 7-epigrandidone A ( 1b ) (ca. 15:1), whereas coleon V ( 7 ) and 5 under the same conditions yield grandidone B ( 2a ) and 7-epigrandidone B ( 2b ) (ca. 3:1). Dimerization of 14-hydroxytaxodione ( 5 ) gives grandidone C ( 3 ; ca. 40%), grandidone D ( 4a ; ca. 50%) and 7-epigrandidone D ( 4b ; ca. 10%). All these compounds obtained by partial synthesis are in every respect identical with the natural products, thus establishing their absolute configurations. The thermal transformation of grandidone C ( 3 ) to grandidone D ( 4a )/7-epigrandidone D ( 4b ) and interconversions of 4a and 4b were achieved. Oxydative addition of coleon U ( 6 ) to 14-hydroxytaxodione ( 5 ) in the presence of Fétizon's reagent mainly leads to grandidone A ( 1a ) and 7-epigrandidone A ( 1b ) (ca. 15:1), whereas coleon V ( 7 ) and 5 under the same conditions yield grandidone B ( 2a ) and 7-epigrandidone B ( 2b ) (ca. 3:1). Dimerization of 14-hydroxytaxodione ( 5 ) gives grandidone C ( 3 ; ca. 40%), grandidone D ( 4a ; ca. 50%) and 7-epigrandidone D ( 4b ; ca. 10%). All these compounds obtained by partial synthesis are in every respect identical with the natural products, thus establishing their absolute configurations. The thermal transformation of grandidone C ( 3 ) to grandidone D ( 4a )/7-epigrandidone D ( 4b ) and interconversions of 4a and 4b were achieved. Oxydative addition of coleon U ( 6 ) to 14-hydroxytaxodione ( 5 ) in the presence of Fétizon's reagent mainly leads to grandidone A ( 1a ) and 7-epigrandidone A ( 1b ) (ca. 15:1), whereas coleon V ( 7 ) and 5 under the same conditions yield grandidone B ( 2a ) and 7-epigrandidone B ( 2b ) (ca. 3:1). Dimerization of 14-hydroxytaxodione ( 5 ) gives grandidone C ( 3 ; ca. 40%), grandidone D ( 4a ; ca. 50%) and 7-epigrandidone D ( 4b ; ca. 10%). All these compounds obtained by partial synthesis are in every respect identical with the natural products, thus establishing their absolute configurations. The thermal transformation of grandidone C ( 3 ) to grandidone D ( 4a )/7-epigrandidone D ( 4b ) and interconversions of 4a and 4b were achieved. Oxydative addition of coleon U ( 6 ) to 14-hydroxytaxodione ( 5 ) in the presence of Fétizon's reagent mainly leads to grandidone A ( 1a ) and 7-epigrandidone A ( 1b ) (ca. 15:1), whereas coleon V ( 7 ) and 5 under the same conditions yield grandidone B ( 2a ) and 7-epigrandidone B ( 2b ) (ca. 3:1). Dimerization of 14-hydroxytaxodione ( 5 ) gives grandidone C ( 3 ; ca. 40%), grandidone D ( 4a ; ca. 50%) and 7-epigrandidone D ( 4b ; ca. 10%). All these compounds obtained by partial synthesis are in every respect identical with the natural products, thus establishing their absolute configurations. The thermal transformation of grandidone C ( 3 ) to grandidone D ( 4a )/7-epigrandidone D ( 4b ) and interconversions of 4a and 4b were achieved. 相似文献
80.
Irja Piirma V. R. Kamath Maurice Morton 《Journal of polymer science. Part A, Polymer chemistry》1975,13(9):2087-2102
A study has been carried out on the kinetics of persulfate-initiated emulsion polymerization of styrene in the presence of an anionic (oleate) or mixed anionic-nonionic emulsifier. In both cases it appears that Smith-Ewart kinetics are obeyed, i.e., there is a constant-rate period up to 40–50% conversion, during which there is a concomitant constant molecular weight development. The sharp increases in molecular weight with conversion reported by Grancio and Williams appear to be an artifact resulting from the use of an impure emulsifier (Triton X-100), which acts as a chain transfer agent to reduce the molecular weight by approximately an order of magnitude. Hence there does not appear to be any kinetic justification for assuming an inhomogeneous swollen latex particle (“core-shell” morphology), and normal thermodynamic considerations should still apply to this swelling phenomemon. 相似文献