Mass spectrometry of sesquiterpenoids of the carotane series. Influence of various methods of ionization on the fragmentation of sesquiterpenols

The mass spectra of five natural sesquiterpenols with various methods of ionization have been studied. A distinct direction of breakdown according to the alternative positions of the OH group at the C-4 or C-5 atom for the skeleton has been found. It has been established that the use of chemical ionization and of secondary-ion mass spectrometry raises the intensity of the molecular ions and increases specific directions of fragmentation.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 522–525, July–August, 1993.     

Mass spectra of diterpene alkaloids with the hetisine skeleton

An analysis of literature material has shown that the stability of the M⁺ ions of bases with the hetisine skeleton decreases considerably when an OR group is present at C-1, C-6, or C-9. The directions of fragmentation are not monotypical and depend greatly on the positions of the oxygen substituents. A similar conclusion can be made from a study of the group and individual features of the breakdown of hetisine, nominine, talatisine, and their derivatives revealed with the aid of high-resolution mass spectrometry and MD spectra. An unusual property of these spectra is the formation of nitrogen-free fragments. The mass spectra of hetisine alkaloids of a new type — zeraconine and its N-oxide — have been characterized.Institute of the Chemistry of Plant Substances of the Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 542–553, July–August, 1987.     

Characteristics of the mass spectra of ecdysteroids with different numbers of -OR groups

The mass spectra of 15 phytoecdysteroids and acetyl derivatives have been compared. With a decrease in the number of -OR groups, the contribution of cleavages of the bonds of the steroid skeleton increases. 20,22-Diols are characterized by the greatest significance of fragmentation at the C-20–C-22 bond. In all the spectra, clear indications of fragmentation of the side chain at the C-22–C-23, C-23–C-24, and C-24–C-25 bonds are observed.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 518–528, July–August, 1980.     

Features of the mass spectra of C18-diterpene alkaloids

Fragmentation under electron impact of eleven C₁₈-diterpene alkaloids with an oxygen function at C-4 has been investigated. The contributions of various modes of forming the (M - CH₃)⁺ ions have been determined. The mechanism of the appearance of the fragments (M - CH₃)⁺ and (M - OCH₃)⁺ at the expense of the methoxy groups at C-14 and C-16 has been considered. The characteristic nature of the parameters of the metastable peaks in the transitions to these daughter ions has been shown. Minor directions of the fragmentation of 3,4-epoxy- and 4-hydroxy bases have been characterized.Institute of the Chemistry of Plant Substances, Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 95–106, January–February, 1989.     

Secondary-ion mass spectrometry of lycotetraosides of the spirostan and furostan series

The secondary-ion mass spectra of seven steroid lycotetraosides have been obtained by the SIMS method. On the use of a glycerol matrix, all the compounds of the spirostan series, including those with an additional carbohydrate substituent a C-24, formed the (M+H)⁺ ions, while a lycotetraoside of the furostan series formed the (M–H₂O+H)⁺ ion. They subsequently decomposed by the alternative successive elimination of the terminal carbohydrate units of the lycotetraose. Substituents at C-25 and C-26 were ejected in the form of glucose molecules. Fragments of the aglycon and of the lycotetraoside moieties of the molecules were recorded. When NaCl was added to the same matrix, all the compounds gave preferentially the (M+Na)⁺ and (M+2Na–H)⁺ ions.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. All-Union Scientific-Research Institute of Agricultural Biotechnology, Lenin All-Union Academy of Agricultural Sciences, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 53–58, January–February, 1991.     

Chemical-ionization mass spectra of diterpene alkaloids

The chemical-ionization spectra of diterpene alkaloids have been investigated for the first time with the recording of positive and negative ions [Cl(+) and (–)). A comparison has been made of the CI(+) spectra with the EI and SIMS spectra. It has been shown that the nature of the CI(+) and (–) spectra depends greatly on the type and position of substituents in the lycoctonine skeleton.Deceased.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 89 14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 114–122, January-February, 1995. Original article submitted October 31, 1994.     

A mass spectrometric study of some triterpenes of the dammarane series

Summary 1. The mass spectra of tetracyclic triterpenes of the dammarane series with substituents at C-3, 6, and 12 and with side chains of various structures have been studied.2. The main direction of fragmentation is the formation of ions as the result of the decomposition of the side chain and of ring C, the second type of fragmentation being controlled by the structure of the side chain.Institute of Biologically Active Substances of the Far-Eastern Scientific Center of the Academy of Sciences of the USSR. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 286–294, May–June, 1971.     

Mass-spectrometric investigation of some new derivatives of the alkaloid lupinine

The mass spectra of some new derivatives of lupinine have been studied with the use of the spectra of metastable ions. On the basis of the results of an investigation of DADI spectra it has been shown that in the formation of low-mass quinolizidine ions the ions with m/z 152–150 are of considerable importance.A. S. Sadykov Institute of Biororganic Chemistry, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 508–512, July–August, 1990.     

Mass spectra of pseudoguaianolides related to carpesiolin

The main directions of fragmentation and the EI of six pseudoguaianolides related to carpesiolin have been studied. It has been established that acylation of the OH group at C-6 suppresses the selective breakdown of the guaiane skeleton, while the simultaneous presence of AcO groups at C-2 and C-4 favors the formation of a number of characteristic ions. The hydrogenation of the exomethylene group has no appreciable influence on direction of fragmentation.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 530–535, July–August, 1993.     

Circular dichroism and stereochemistry of the C-20 and C-22 asymmetric centers of 17-isoxazolinyl- and 20-hydroxy-20-isoxazolinylsteroids

The CD spectra of a number stereoisomeric isoxazolinylsteroids have been investigated. Starting from established rules, it has been shown that this method can be used to determine the configurations of the C-20 and C-22 centers of the 17- and 20-isoxazolinylsteroids studied.The numbering of the atoms of the isoxazoline ring corresponds to the numbering of the side-chain of cholesterol.Institute of Bioorganic Chemistry, Belarus Academy of Sciences, Minsk. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 391–397, May–June, 1994.     

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.     

13C NMR spectra of biologically active compounds XI. Diastereomeric effects in C-glycosides

The¹³C NMR spectra of epimeric C-D-glucopyranosides with alkyl, aryl, and alkynyl substituents have been studied. The diastereomeric effects of the chemical shifts have been determined and assignments have been made to the 1-and 1- stereochemical series on the basis of HH COSY and CH HET CORR two-dimensional NMR spectra. The diastereomeric effects observed for the C-3 and C-5 carbon atoms are proposed as characteristic parameters for establishing the stereochemistry at the C-1 carbon atom.Institute of Chemistry, Bashir Scientific Center, Urals Branch, Academy of Sciences of the USSR, Ufa. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 368–373, May–June, 1991.     

Nature of the transformations of oleanolic acid in an acid medium

3-Trifluoroacetoxyoleanolic acid and 3-trifluoroacetoxyolean-13(18)-en-28-oic acid have been isolated from the mixture of the products of the transformation of oleanolic acid in a trifluoroacetic acid medium, and their structures have been established with the aid of IR, PMR and mass spectra. The formation of these products indicates an unambiguous route of the stabilization of the intermediate carbocation with the charge on the C-13 atom. The hydroxy group at C-3 is esterified by the trifluoroacetic acid.All-Union Scientific-Research Institute of Medicinal Plants, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 320–323, May–June, 1986.     

Mass spectrometric study of sophoramine isomers by the direct analysis of daughter ions (DADI)

In a study of the mass spectra of sophoramine, isosophoramine, and neosophoramine by the direct analysis of daughter ions (DADI) it has been established that the ions with m/e 149 and 136 are formed from the molecular ions. Differences have been found in the DADI spectra of the alkaloids studied that are due to features of the three-dimensional structures of their molecules.V. I. Lenin Tashkent State University. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 353–355, May–June, 1979.     

Ionization processes accompaning interaction of excited atoms with CH3CN,CH3COOH,and HCOOH molecules

The fragmentation processes of the molecular ions formed as a result of single collisions of metastable and highly excited Rydberg atoms of noble gases with molecules of acetonitrile, formic acid, and acetic acid have been investigated by a mass-spectrometric method. The correlation between the observed Penning-dissociativeionization mass spectra and the degree of overlap of the moelcular orbitals with vacant orbitals of the metastable atoms determined from the available energy spectra of the electrons formed during Penning ionization has been examined. Complex ions appearing during associative ionization have been discovered. The mechanisms for the formation of the observed ions have been discussed.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 26, No. 1, pp. 39–46, January–February, 1990.     

Field-desorption mass spectra of flavonoid acylglycosides. II. Natural cinnamoyl and benzoyl derivatives

The field-desorption mass spectra of 14 flavonoid glycosides esterified with p-coumaric, ferulic, caffeic, p-hydroxybenzoic, and gallic acids have been studied. For all the compounds the molecular ions and the ions of the aglycone (A) were obtained as the main peaks. The spectra also contained a number of other fragmentary ions, including the ion of the acylated anhydrosugar. For flavonol glycosides in which the carbohydrate is esterified by cinnamic acids, the (A + Ac), and for the diacylglycosides the (A + 2 Ac), ions are diagnostic. The formation of these strong ions corresponding in mass to the molecules of the mono- and diacylated aglycone permits the assumption of the existence of acyl migration in the breakdown of the initial molecular ion.All-Union Scientific-Research Institute of Medicinal Plants, Moscow. L. Ya. Karpov Scientific-Research Institute of Physical Chemistry. Irkutsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 582–589, September–October, 1984.     

Mass spectrometic investigation of the structure and formation mechanism of ions in the autoionization of aliphatic alcohols

The structure and formation mechanism of ions in the field ionization of methanol and ethanol have been studied by isotopic labeling with O¹⁸ and deuterium, and mass spectrometric analysis. It is shown that these alcohols give identical mass spectra in the molecular ion region, these consisting of four lines: M+1, M, M–1, and M–2. The M+2 ions have the structure ROH·H⁺ while the M–1 ions are (R–H)·OH⁺. For methanol the M–2 ions have the structure of formaldehyde, and for ethanol they have those of both an aldehyde and a vinyl alcohol. It is also shown that field ionization may be used to study the catalytic oxidation of alcohols over platinum by free oxygen.     

Photoionization mass spectrometry of aliphatic monoterpene alcohols

Summary 1. The dissociative processes observed in the photoionization of monoterpene alcohols have been investigated. It has been established that the relative intensities of the peaks of the heavy ions, including the molecular ions, are higher on photoionization than on electron impact.2. It has been found that the mass spectra of the isomeric alcohols obtained on photoionization differ from one another to a greater degree than the electronic mass spectra.Agrophysical Scientific-Research Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 723–726, November–December, 1974.     

Secondary-ion mass spectrometry of some catalpol and mussaenoside derivatives

The iridoid glycosides catalpol, veronicoside, catalposide, mussaenoside, and 8-epiloganin have been investigated by secondary-ion mass spectrometry (SIMS). A tendency of these compounds to give cationized1 form of the molecular ions in the SIMS regime has been shown. In the SIMS spectra of veronicoside and catalposide the maximum peaks were those of acyl cations, and in the cases of mussaenoside and 8-epilonganin they were the peaks of ions formed by the elimination of a glucose molecule.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 89 14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 62–65, January–February, 1996. Original article submitted Spetemebr 17, 1995.     

V. Mass spectrometry of the alkaloids ofArundo donax

The mass spectra of alkaloids isolated from the epigeal part of the plant Arundo donax L. have been investigated. The main pathways of fragmentation under electron impact have been determined for arundine, ardine, donaxaridine, donaxarine, and donaxinine. An analogy has been found in the fragmentation of the M⁺ ions of donaxarine and donaxinine, the main pathway of their fragmentation consisting in the elimination of the elements of the N-methylpyrrolidone ring.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 89 14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 217–220, March–April, 1996. Original article submitted September 25, 1995.