Features of the mass spectra of hetisine bases with an OH group at C-14

The EI mass spectra of five hetisine bases with an OH group at C-14 have been investigated. The main directions of fragmentation are initiated by the cleavage of the C-14-C-20 bond. With the aid of measurements of the elementary compositions of the molecular and fragmentary ions and of a comparison of the B/E linked-scanning and metastable defocusing spectra, the mechanism of the formation of the key fragments has been established and alternative methods for the production of certain ions have been revealed.Institute of Chemistry of Plant Substances, Uzbekistan Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 82–89, January–February, 1992.     

Spectra of the metastable ions on steroid sapogenins and their dihydro derivatives

Characteristic distinguishing features of the mass spectra of steroid sapogenins of the spirostan series and their dihydroderivatives are considered. The MD and B/E = const spectra of all the key ions have been studied. It has been established that the relative intensities of the metastable peaks obtained by the two methods have close values. The orders of these magnitudes are the same for monotypical fragmentation processes. The correlation between the parameters of the spectra is disturbed if a daughter of one has a number of alternative formation pathways. On the whole, the linked-scanning spectra are characteristic to the extent that they contain metastable peaks of analogous transitions possessing close parameters.Institute of Chemistry of the Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Special Design Bureau of Analytical Instrument Construction, Scientific and Technical Branch, Academy of Sciences of the USSR, Leningrad. Translated from Khimiya Priorodnykh Soedinenii, No. 4, pp. 489–497, July–August, 1990.     

Fragmentation of sesquiterpene lactones related to leucomisin

The mass spectra of seven sesquiterpene lactones — leucomisin, austricin, parishin B, parishin C, matricarin, artelin, and artelin diacetate — have been studied. It has been shown that the presence of the conjugated bonds C(1)=C(10), C(2)=0, and C(3)=C(4), and also C(5)=C(6), stabilizes M⁺, and the main fragmentation process is that of the splitting out of the lactone ring. The presence of hydroxy substituents at C(3) and C(8) of the guaiane system does not change the stability of M⁺ under electron impact. The directions of fragmentation have been confirmed by an analysis of spectra obtained by the metastable defocussing of daughter ions and by measuring the accurate masses of the main peaks of the fragmentary ions.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 96–101, January–February, 1987.     

Use of the method of metastable defocusing for the analysis of the processes involved in the fragmentation of lycoctonine bases

The metastable transitions in the mass spectra of 21 lycoctonine bases have been studied by the method of metastable defocusing (MD). It has been established that as a criterion of the monotypicity of single-stage fragmentation reactions it is possible to use a linear dependence of the relative intensities of the metastable peaks (MPs) on the stability of the daughter ion. In the MD spectra of the ions formed in several stages, to characterize the generality of the breakdown reactions, in addition to the intensities of the MPs, the accurate positions of their maxima and the general shape of the curve are important.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 481–495, July–August, 1984.     

B/E linked scanning spectra of the molecular and fragmentary ions of lycoctonine bases

The B/E linked scanning spectra of the M⁺, (M-15)⁺, and (M-OR₁)⁺ ions and those of some other series have been investigated. The characteristic nature of the individual intensities of the metastable peaks (the magnitudes A) with the same R₁ radicals for different groups of alkaloids has been shown for the spectra of the M⁺ and (M-15)⁺ ions. The reason for the quantitative differences of the B/E spectra of the (M-OH)⁺ ions from the spectra of the (M-OCH₃)⁺ and (M-OAc)⁺ ions, consisting in the influence of alternative methods of eliminating an OH radical, has been found. It has been confirmed that the values of A of analogous transitions calculated from the B/E and MD spectra are close to one another. On the other hand, the values of the energy of the metastable transitions obtained by these two methods differ from one another by two orders of magnitude.Institute of Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Special Design Bureau of Analytical Instrument Construction, Scientific and Technical Branch, Academy of Sciences of the USSR, Leningrad. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 72–84, January–February, 1991.     

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.     

Mass-spectrometric behavior of oxidized triacylglycerols and their TMS derivatives

The mass spectrometric fragmentation of oxidized triacylglycerols of castor oil and their TMS derivatives have been studied for the first time. Three types of fragmentary ions have been detected: 1) products of the successive elimination of TMSOH; 2) ions characteristic for unoxidized triacylglycerols; and 3) products of the cleavage of C-C bonds present in the -positions to the TMSO groups, which are characteristic for these hydroxy acid derivatives. The origin of these ions has been confirmed by measurements of elementary composition and by the analysis of MD spectra. The specific cleavage of the C-C bonds in the -positions to the OTMS (OH) groups permits the mass-spectrometric method to be proposed for the analysis of mixtures of oxidized triacylglycerols.Institute of the Chemistry of Plant Substances of the UzSSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 551–558, September–October, 1986.     

Investigation of the behavior of substituted benzimidazoles under the influence of electron impact

The mass spectra of eight benzimidazole derivatives were studied. The effect of the nature and position of the substituent on the principal pathways of the fragmentation of the molecular ion, which involve competitive detachment of an HCN particle and the substituent, was examined. The formation of rearranged ions in all cases was confirmed by metastable transitions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 819–822, June, 1984.     

Mass spectra of a number of 1,3,2-oxazaphosphorinanes

The mass spectra of a number of 1,3,2-oxazaphosphorinanes were obtained. The possibility of the mass spectrometric identification of this class of compounds, including the isomers that differ with respect to both the nature of the alkoxy groups attached to the phosphorus atom and the size of the ring, was demonstrated. The principal pathways of dissociative ionization of the investigated molecules were established by comparison of the mass spectra and the fragmentation reactions of the metastable ions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 749–752, June, 1977.     

Features of mass-spectrometric fragmentation of racemic diptocarpidine and diptocarpiline

The mass-spectrometric fragmentation of the positive and negative molecular ions of diptocarpidine and diptocarpiline and of two model compounds have been studied, and it has been shown that the formation of the fragmentary ions takes place both by direct bond cleavage and with the involvement of complex skeletal rearrangements. The composition of the rearranged ions formed from M⁺ has been confirmed with the aid of high-resolution mass spectrometry. An intramolecular interaction of the this (sulfoxy) and urea groups as a consequence of the existance of the molecules under investigation in a folded conformation has been established.Institute of Chemistry Bashkir Branch USSR Academy of Sciences, Ufa. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 390–396, May–June, 1988.     

Mass-spectrometric behavior of oxidized triacylglycerols and their TMS derivatives

The mass spectrometric fragmentation of oxidized triacylglycerols of castor oil and their TMS derivatives have been studied for the first time. Three types of fragmentary ions have been detected: 1) products of the successive elimination of TMSOH; 2) ions characteristic for unoxidized triacylglycerols; and 3) products of the cleavage of C-C bonds present in the α-positions to the TMSO groups, which are characteristic for these hydroxy acid derivatives. The origin of these ions has been confirmed by measurements of elementary composition and by the analysis of MD spectra. The specific cleavage of the C-C bonds in the α-positions to the OTMS (OH) groups permits the mass-spectrometric method to be proposed for the analysis of mixtures of oxidized triacylglycerols.     

Mass spectra and structures of isomeric phenylaminopyrazoles

The processes involved in the dissociative ionization of isomeric phenylaminopyrazoles under the influence of electron impact were studied. The pathways of fragmentation of the molecular ion (M⁺) were proved rigorously by means of the spectra of the metastable ions. The empirical compositions of the fragment ions were confirmed by the high-resolution mass spectra. It was established on the basis of the mass spectra of the amino-group-deuterated analogs that M⁺ exists exclusively in the amide from. A rearrangement leading to the formation of benzodiazepine cation radicals precedes fragmentation of M⁺. The elimination of an HCN particle in the first step of the fragmentation of M⁺ does not involve the amino group. The pK_a values are presented for all of the investigated phenylaminopyrazoles.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1381–1388, October, 1978.     

Mass spectrometry of metastable ions from lagochiline-type diterpenoids

Low-and high-resolution mass spectra and spectra of metastable ions were studied using direct analysis of daughter ions (DADI) and metastable defocusing (MD) of lagochiline-type diterpenoids. Patterns in their fragmentation were found. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 56–60, January–February, 2007.     

Use of the method of metastable defocusing for the analysis of the processes involved in the fragmentation of lycoctonine bases

The metastable transitions in the mass spectra of 21 lycoctonine bases have been studied by the method of metastable defocusing (MD). It has been established that as a criterion of the monotypicity of single-stage fragmentation reactions it is possible to use a linear dependence of the relative intensities of the metastable peaks (MPs) on the stability of the daughter ion. In the MD spectra of the ions formed in several stages, to characterize the generality of the breakdown reactions, in addition to the intensities of the MPs, the accurate positions of their maxima and the general shape of the curve are important.     

Metastable-ion mass spectra of insect pheromones

The laws of the fragmentation of the metastable molecular and key fragmentary ions of mono- and dienic alcohols, acetates, aldehydes, hydrocarbons, and epoxy compounds forming components of the pheromones of the turnip, tomato, and bollworm moths and other pests of agricultural crops are discussed, and the use of the laws found in the identification of compounds of this class has been demonstrated.Institute of Bioorganic Chemistry, Academy of Sciences of the Republic of Uzbekistan, Tashkent, FAX 62 70 71. Tashkent State University, FAX 46 24 72. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 455–470, July–August, 1994.     

identification of the sterols of the yeasts Saccharomyces cerevisiae and Candida guilliermondii by the mass-spectrometric method

The sterol compositions of mutants of the yeasts ofSaccharomyces cerevisiae andCandida guilliermondii have been characterized by the methods of GLC, TLC, UV spectroscopy, and chromato-mass spectrometry. The possibility has been shown of identifying yeast sterols on the basis of a comparison of the intensities of the peaks of the fragmentary ions having a common nature for all sterols (m/z200). A change in the sterol composition in mutant yeasts as compared with the initial strain has been detected which is obviously connected with the blockage of the routes for the biosynthesis of ergosterol in the yeast cell.Lensovet Leningrad Technological Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 196–201, March–April, 1986.     

Differences in the mass spectra of isomeric benzolactams

It is shown that 3- and 4-substituted dihydro-2-quinolones can be distinguished from the isomeric dihydro-1-isoquinolones by mass spectrometry. The [M - CO]⁺ ion is characteristic for the mass spectra of dihydroquinolone derivatives, whereas retrodiene fragmentation of the molecular ion is characteristic for dihydroisoquinolone derivatives. The intense [M - R]⁺ and [M - R, - H₂O]⁺ ion constitute evidence that the substituent is located in the 3 (for dihydroisoquinolones) or 4 (for dihydroquinolones) position. The processes that occur in the fragmentation were confirmed by data from the high-resolution mass spectra, an analysis of the observed metastable ions, and an analysis of the mass spectra of 3-methyl-3,4-dihydro-1-isoquinolone and 4-methyl-3,4-dihydro-2-quinolone containing deuterium attached to the nitrogen atoms.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 246–249, February, 1979.     

Mass spectra of 1-alkoxyaziridines

The mass spectra of 12 di-, tri-, and tetramethyl-substituted 1-alkoxyaziridines were investigated, and the principal pathways of their fragmentation under the influence of electron impact, which include cleavage of the N-O and C-O bonds of the alkoxy group or cleavage at two bonds of the aziridine ring, were ascertained. The compositions of the resulting ions were confirmed by high-resolution massspectrometric data. The four examined parallel fragmentation processes explain the appearance of all of the principal ions in the mass spectra of alkoxyaziridines. The established principles open up the possibility of identification of 1-alkoxyaziridines in complex mixtures with isomeric compounds.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 329–337, March, 1978.     

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 spectrometry of heterocyclic compounds—III. Electron-impact-induced fragmentation of 1,2-benzisothiazole and some 3-substituted derivatives

The mass spectra of fifteen 1,2-benzisothiazoles are reported; their fragmentation patterns have been investigated by labelling experiments, high resolution mass measurements and defocused metastable ion detection. The parent compound of the series, 1,2-benzisothiazole, eliminates HCN after partial inter-ring hydrogen scrambling. The extent of scrambling has been determined for normal daughter ions produced at different electron beam energies and also for metastable daughter ions, and is compared with the data reported for benzothiazole. Some 3-substituted derivatives show unusual fragmentation patterns. The mechanisms of these processes are under further investigation.