全乙酰化低聚木糖的质谱研究

本文报道了全乙酰化木糖(1)～木六糖(6)的电子轰击质谱(70eV,20eV)及化学电离(反应气体CH_4,i-C_4H_(10),NH_3)质谱的研究结果.根据亚稳峰及高分辨测定资料,阐述了木糖全乙酰化物的碎裂途径,讨论了木二糖～木六糖全乙酰化物的碎裂机理,指出了低聚木糖质谱的特征碎片离子.在所研究的电子轰击质谱中均未观察到分子离子,只有以NH_3为反应气体的化学电离质谱才获得准分子离子,其中全乙酰化木糖(1)～木三糖(3)的[M+NH_4]~+为基峰,而全乙酰化木四糖(4)～木六糖(6)的[M+NH_4]~+离子强度较弱。     

Mass spectra of furostanol glycosides

The mass-spectrometric fragmentation of furostanol glycosides under electron impact is described, and a comparison is made of these spectra with the secondary-emission spectra obtained by the FABMS and LSIMS methods.Institute of Chemistry of Plant Substances, Uzbekistan Academy of Sciences, Tashkent. Institute of the Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Pushchino. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 93–98, January–February, 1992.     

Mass spectrometry of pennogenin glycosides

The electron-impact mass spectra of five unesterified pennogenin glycosides, which contain the M⁺ or (M - H₂O)⁺ peaks, have been obtained. The characteristic features of the fragmentation of these compounds have been studied. In addition to ions characterizing the successive elimination of carbohydrate units, fragments have been detected which show the breakdown of the terminal pyranose ring. Five new directions of the fragmentation of the spirostanol skeleton due to the presence of an OH group at C-17 have been found.Institute of the Chemistry of Plant Substance, Academy of Sciences of the Uzbek SSR, Tashkent. Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Science Center of the Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 337–341, May–June, 1986.     

Mass spectrometry of oleanolic acid glycosides

Conclusions An analysis of the mass spectra of the oleanolic acid glycosides makes it possible to determine the nature of the carbohydrate moieties and the site of their attachment to the genin, and also to reliably identify the nature of the genin.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2713–2718, December, 1973.     

The reactions of beta- and alpha-pyranose peracetates with PCl5, and utilization of the products to construct sarsasapogenin glycosides.

The reactions of beta- and alpha-pyranose peracetates with PCl5 gave products regioselectively chlorinated. The reactions of 1,2,3,4,6-penta-O-acetyl-beta-D-glucopyranose (5) and -beta-D-galactopyranose (6) with PCl5 in CCl4 and that of methyl 2,3,4-tri-O-acetyl-beta-D-glucuronatopyranose (7) with PCl5 in toluene gave 2-O-trichloroacetyl-beta-D-pyranosyl chlorides 4, 12 and 14, respectively, as major products, and alpha-D-pyranosyl chlorides 11, 13 and 15, respectively, as minor products. On the other hand, the reactions of compounds 8 and 9 which were alpha-anomers of 5 and 6, respectively, with PCl5 gave as major products transformed acetyl groups at C-6 to -C(Cl) = CCl2 or -C(Cl)2-CCl3 group (16 and 17 from 8 and 18 from 9). The same reaction of 10, which was alpha-anomer of 7, gave alpha-chloride 15 as a major product. The glycosidation of sugar derivative 4 with sarsasapogenin 23 gave beta-glycoside 24 (29.1%) and alpha-glycoside 25 (46.9%), and that of 12 with 23 gave beta-glycoside 26 (24.0%) and alpha-glycoside 27 (40.8%). The improvement of the yields of beta-glycosides 24 and 26 (66.9 and 62.1% for 24 and 26, respectively) in the glycosidations were accomplished by the employment of alpha-bromides 28 and 29 obtained from 4 and 6, respectively. The glycosidations of monoglycosides 30 and 31 obtained by the treatment 24 and 26, respectively, with ammonia-saturated ether with sugar acetate bromides 32 and 34 gave diglycoside derivatives 35 and 33, respectively.     

Mass spectrometry of glycosides of oleanolic acid

Conclusions The mass spectra of oligosides of oleanolic acid were studied. The site of addition of the carbohydrate component to the oleanolic acid residue, the nature of the substituting sugars, and the position of the glycoside bonds between them can be determined according to their nature.For communication 1, see [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 113–121, January, 1974.     

Mass spectrum of nitromethane

The mass spectrum of nitromethane points to rupture of the CH₃? NO₂ bond as the dominant primary reaction, as also observed in pyrolysis, photolysis and radiolysis. Isomerization of the molecular ion to the nitrite configuration seems to contribute little in the mass spectrum of nitromethane, in contrast to those of nitrobenzene and other nitroarenes. The nitrite ion is probably the immediate precursor of [NO]⁺ at its appearance potential, but most of the [NO]+ yield seems to stem from secondary decomposition of excited [NO₂]⁺.     

Triterpene glycosides ofAstragalus and their genins

The roots of Astragalus taschkendicus Bunge (Leguminosae) have yielded the new cycloartane glycoside askendoside F which is 24R-cycloartan-3β,6α,16β,24, 25-pentaol 3-O-[O-α-L-arabinopyranosyl-(1→2)-β-D-xylopyranoside] 25-O-D-glucopyranoside, and D-3-O-methyl-chiro-inositol.     

EI and IKE spectra of some aldosyl disaccharide peracetates

The electron ionisation and ion kinetic energy spectra of some aldosyl disaccharide peracetates are discussed. The diagnostic value of the data in differentiating between the various types of glycosidic linkages is emphasised.     

Transformations of ecdysteroids in the synthesis of their structural analogs and minor phytoecdysteroids

The review considers transformations of ecdysteroids (mostly of 20-hydroxyecdysone and its derivatives) involving the A, B, C, and D rings of the steroid skeleton and the side chain, which are used in the synthesis of minor phyto- and zooecdysteroids and structural analogs of ecdysteroids.     

Flavonoids and their glycosides, including anthocyanins

This review describes more than 600 new examples of naturally occurring flavonoids found either as aglycones or glycosides, comprising flavones, flavonols, chalcones, dihydrochalcones, aurones, flavanones, dihydroflavonols, anthocyanidins and anthocyanins. The main topics addressed are source, identification, biological activity, biosynthesis, synthesis, and ecological or chemosystematic significance, and 514 references are cited.     

Triterpene glycosides ofHedera helix III. Structure of the triterpene sulfates and their glycosides

From the leaves of English ivyHedera helix L. we have isolated the known 3-sulfates of oleanolic and echinocystic acids and their 28-O--L-rhamnopyranosyl-(14)-O--D-glucopyranosyl-(16)-O--D-glucopyranosyl esters and the new 3-sulfate of 28-O--gentiobiosyl oleanolate — helicoside L-8a. The structures of the compounds isolated were deduced from the results of chemical transformations and NMR spectroscopy.Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 87–90, January–February, 1999.     

Regio and stereo directional oxidation of ecdysteroids and their 7,8-dihydroanalogs with ozone in pyridine

The oxidation of ecdysteroids and their 7,8-dihydroanalogs with ozone in pyridine occurred regio- and stereoselectively at the hydroxy groups of the A ring giving 2-dehydro-3α-hydroxy derivatives.