Mass-spectrometric study of physiologically active β-thiosemicarbazones of N-alkylisatins

The molecular ions of isatin (I) and N-methyl- (II) and N-ethylisatin (III) -thiosemicarbazones undergo fragmentation via many pathways with the elimination of NH₃, H₂S, CO, CH₂N₂, CHN₃, CH₂N₂S, CH₂NS, and CHNS particles; this is due to primary localization of the charge on the heteroatoms of the thiosemicarbazone residue. A previously unknown rearrangement, which consists in migration of an HS group to the -carhon atom of the heteroring with subsequent ejection of a CHN₃ fragment. The [M — CO]⁺ ions undergo fragmentation with the elimination of CH₂N₂S; in the case of II and III fragmentation is preceded by detachment of a hydrogen atom (II) or a methyl group (III) from the substituent attached to the ring nitrogen atom. The [M — CO, -H, -CH₂NS]⁺ (II) and [M — CO, -CH₃, -CH₂N₂S]⁺ (III) ions undergo fragmentation with the ejection of HCN in two ways through both the ring nitrogen atom and the thiosemicarbazone residue. Schemes for the principal pathways of fragmentation and rearrangements are presented. The compositions of the ions were confirmed by the high-resolution mass spectra and the mass spectra of the N-deuteroalkyl derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 75–79, January, 1979.     

Mass spectrometric study of isatins II. N-propyl(allyl,propargyl)isatins

The mass spectra of N-propyl- (I), N-allyl- (IV), and N-propargylisatin (VII) and their 5-methyl (II, V, VIII) and 7-methyl (III, VI, and IX) derivatives were recorded. It is shown that a portion of the [M-2CO]⁺ ions in the mass spectra of N-propargylisatins undergo rearrangement to give ions with a quinoline structure. A scheme for the fragmentation of the investigated compounds is presented. The mass spectra of the 5- and 7-methyl derivatives are compared.See [1] for communication I.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 639–641, May, 1977.     

Mass-spectrometric investigation of isatins

It is shown that in the mass spectra of N-alkylisatins with a normal C₁-C₁₀ chain the intensity of the [M-CO]⁺- and [M-(2CO)]⁺. peaks characteristic for isatin and N-methylisatin decreases as the alkyl radical is lengthened, whereas the intensity of the peak formed as a result of successive loss by the molecular ion of a CO group and a portion of the radical as a result of cleavage of the bond at the α-carbon atom increases. Fragments due to α,β,γ... cleavages, both without migration and with migration of the hydrogen atoms, appear in the spectra of N-alkylisatins commencing with chains containing more than two C atoms.