Nachbargruppenbeteiligung bei massenspektrometrischen Fragmentierungsreaktionen: Spermin-Derivate. 18. Mitteilung über das massenspektrometrische Verhalten von Stickstoffverbindungen

The mass spectral behaviour of tetraacetyl spermine ( 2 ) has been investigated. The fragmentation reactions are characterized by the neighbouring group participation of the amide nitrogen atoms. Only a few reactions can be explained by usual pathways (α-cleavage, onium reactions). Most of the fragment-ions are formed by neighbouring group participation:

• 1 [M-COCH₃]⁺-Ion.
• 2 Breakdown of one of the two 1,3-diaminopropan moieties: m/e 242, 256, 268. This type of fragmentation is characteristic for all acetylated 1,3-diaminopropan-derivatives e.g. triacetylspermidine.
• 3 Expulsion of a neutral amine: m/e 169.
• 4 S_Ni-type reactions, by which cyclic ions are formed: m/e 100.

     

Nachbargruppeneffekte bei der massenspektrometrischen Fragmentierung: N-Acetyl-ω-Phenylalkylamine. 20. Mitteilung über das massenspektrometrische verhalten von stickstoffverbindung

The mass spectral behaviour of the difunctional alkane N-acetyl-4-phenyl-butylamine ( 3 ) was investigated. The main fragmentation of compound 3 is caused by the interaction on the two functional groups, which could be shown by comparison of the corresponding monofunctional compounds n-butylbenzene ( 4 ) and N-acetyl-n-butylamine ( 5 ). On the bases of high resolution data, the analyses of metastable transitions and the comparison of the spectra of some homologs and deuterated analogs of 3 the structures and their genesis of the main fragment i ons were deducted.     

Reaktionen von Glutaminsäuredimethylester im Massenspektrometer. 21. Mitteilung über das massenspektrometrische Verhalten von Stickstoffverbindungen

The mass spectral fragmentation of dimethyl glutamate ( 1 ) and its deuterated derivatives 1a , 1b and 1c has been investigated. By loss of a methoxycarbonyl group from the molecular ion an ion of m/e 116 is generated. The latter splits off methanol (m*), the resulting fragment of m/e 84 giving raise to the base peak of the spectrum. Only part of the hydrogen transferred to the leaving group originates from thc amino group, as was suggested earlier [2] [3]. Basing on experiments with deuterated compounds we propose an additional mechanism for the reaction, i.e. hydrogen transfer from C(3) to methoxyl. The fragment generated by both processes is most likely to be a pyrrolinonium ion. Thermal side reactions in the mass spectrometer (formation of pyroglutamic acid ester) followed by fragmentation may lead to the same ion. – The mechanisms discussed are supported by the mass spectral fragmentation of N-acetyl-glutamic acid diesters 3 , 3a , 3b and 3d and of the N, N-dimethyl derivatives 4 and 4a . – The fragmentation reactions investigated are similar to some of 1,3-trimethylenediamine derivatives [7]. This means that there are parallels in the mass spectral fragmentation of difunctional compounds irrespective of the nature of the functional groups.     

Der massenspektrometrische Verlust von Vinylalkohol aus 1-Amino-3-aryloxy-2-propanolen. 24. Mitteilung über das massenspektrometrische Verhalten von Stickstoffverbindungen

Loss of vinyl alcohol from 1-amino-3-aryloxy-2-propanols under electron impact Under electron impact compounds of type 1 (see Scheme 1) split off 44 mass units from the molecular ion. This unusual reaction was studied using derivatives and deuterium labelled compounds. It could be demonstrated that for this fragmentation reaction 16 is the important structural feature from which H₂(C3)?C(2)HOH (44 mass units) is lost. The preferred reaction mechanism involves a transition state in which four members of the side chain are involved (Scheme 2, mechanism 2).     

Das unterschiedliche massenspektrometrische Fragmentierungsverhalten von Lysinmethylester und dessen N,N′-Diacetylderivat. 27. Mitteilung über das massenspektrometrische Verhalten von Stickstoffverbindungen

The Different Behaviour of Lysine Methyl Ester and its N,N′-Diacetyl Derivative under Electron Impact The base peak in the spectrum of lysine methyl ester is due to the fragment ion C₅H₁₀N (m/e 84), for which the cyclic structure g (Scheme 1) is deduced. During its formation from the [M-COOCH₃]-ion an equilibration of both nitrogen atoms takes place (ion c , Scheme 1). The cyclic nature of ion m/e 84 is in agreement with the intensity of the corresponding ions in the spectra of homologues of lysine methyl ester (Fig. 1). Although in comparison with lysine methyl ester ( 1 ) N,N′-diacetyl-lysine methyl ester ( 7 ) shows the same general fragmentation pathway with formation of the ions [M-COOCH₃] and [M-COOCH₃-H₂NCOCH₃] (m/e 126), the exact fragmentation mechanism proves to the different. Two mechanisms are discussed for the formation of the ion m/e 126 from 7 (Schemes 2 and 3). The results are based on the spectra of labelled derivatives.     

Thermische Reaktionen im Massenspektrometer Modellreaktionen zur Untersuchung thermischer Umalkylierungen. 11. Mitteilung über das massenspektrometrische Verhalten von Stickstoffverbindungen

During the introduction of an organic compound into the mass spectrometer thermal reactions can take place before the ionisation process, thus changing the structure of the compound. On the basis of known experimental results the following reactions, which are independent of electron bombardment are discussed: decarboxylation, dehydration, loss of alcohols, decarbonylation, decomposition of carboxylic esters, retro aldol reaction and similar processes, retro DIELS -ALDER reaction, isomerisation, disproportionation, hydrogenolysis-dehydrogenolysis, transalkylation, dimerisation, and pyrolysis of quaternary nitrogen containing compounds. Finally, the results of novel model reactions concerning thermal transalkylation are discussed.     

Massenspektrometrische Identifizierung und Synthese isomerer und homologer Spermidin- und Spermin-Derivate. 25. Mitteilung über das massenspektrometrische Verhalten von Stickstoffverbindungen. 161. Mitteilung über Alkaloide

Synthesis of isomeric and homologous spermidine and spermine derivatives and their identification by mass spectrometry. The structure of homologous and isomeric spermidines and spermines follows from mass-spectroscopical analysis of their peracetyl (see text, footnote 3) (Table 1) or tosyl-acetyl (Table 2) derivatives. In the case of the peracetyl compounds, triads of peaks are recorded which, according to the number of methylene groups between the nitrogen atoms, show mass numbers characteristic for each of the substances (Scheme 1, ions b , d , e and c ). On the basis of cyclic ions of type f (Scheme 2), occurring in the mass spectra of N-acetyl derivatives, tosylated on a secondary amino nitrogen atom, deductions can be drawn as to the number of methylene groups between neighbouring tosylated and acetylated nitrogen atoms in these compounds.     

SN-2-artige massenspektrometrische Fragmentierungen bei substituierten N-Alkylpiperidinen. 10. Mitteilung über das massenspektrometrische Verhalten von Stickstoffverbindungen [1]

An S_N2-type fragmentation was observed on mass spectrometric analysis of N-(ω-X-alkyl)-2-alkylpiperidines (X = NRCOR′,  CONH₂,  COOR,  NH₂). The molecular ion after loss of the 2 alkyl substituent on the piperidine ring may eject the neutral piperideine on attack of the substituent X on the α-carbon of the N-substituted alkyl-chain. Through this process a cyclic fragment ion is formed. The influence of its ring size and of the substituent X on the stability of this fragment was investigated. The S_N2 reaction is favoured in the case of production of five- and six-membered rings.     

Substituenteneinfluss bei der massenspektrometrischen Fragmentierung: Untersuchungen an N-methyl-β,β′-diphenyl-diäthylaminen. 19. Mitteilung über das massenspektrometrische Verhalten von Stickstoffverbindungen

Some different substituted N-methyl-β,β′-diphenyl-diethylamines (I) were investigated mass spectrometrically. The main fragmentations and their genesis are summarized in Scheme 2. The molecular ion generates the major fragmentions a (m/e 148) and b (m/e (147 + X)); c (m/e 105) is formed from a and d (m/e (104+X)) from b by further decomposition. The logarithms of the ratios of the relative ion intensities a/b , c/a and d/b were correlated according to the Hammett equation with different substituent constants. The following correlation coefficients (at 20ev) were found: r = 0,98 (σ⁺), r = 0,63 (σ) and r = 0,96 (σ) respectively. On the basis of the above Hammett correlations, the value of this kind of investigation for the elucidation of mass spectral fragmentation mechanisms is discussed.     

Ammoniakverlust aus α,ω-Alkandiaminen im Massenspektrometer. 22. Mitteilung über das massenspektrometrische Verhalten von Stickstoffverbindungen

Loss of ammonia from α,ω-alkanediamines in the mass spectrometer . Under electron impact α,ω-alkanediamines lose ammonia from the molecular ion. This fragmentation reaction is explained in the case of 1.4-butanediamine ( 1 ) on the basis of the spectra of homologues and deuteriated derivatives. The reaction proceeds via neighbouring group participation; the mechanism is given in Scheme 1.     

Massenspektrometrische Untersuchung von Pleiocarpamin-Derivaten. 9. Mitteilung über das massenspektrometrische Verhalten quartärer Stickstoffverbindungen [1]

Mass spectrometric analysis of quaternary nitrogen compounds has shown that three principal thermal processes occur, namely dealkylation, Hofmann degradation and substitution. Only in the cases of dealkylation and the Hofmann degradation has direct chemical evidence been previously obtained. The first part of this paper presents mass spectrometrical and chemical evidence for the pyrolytic formation of a substitution product, e. g. 5 . By means of different deuterated derivatives the mechanisms of fragmentation of the mavacurine derivative ϵ₂-dihydromavacurine methochloride ( 8 ) and of the corresponding Hofmann base ( 14 ) have been formulated.     

Beitrag zur massenspektrometrischen retro-Diels-Alder-Reaktion: 1,2,3,4-Tetrahydrophenanthren. 35. Mitteilung über massenspektrometrische Untersuchungen

Contribution to the Mass Spectral retro-Diels-Alder Reaction: 1,2,3,4-Tetrahydrophenanthrene [1,4-¹³C]-1,2,3,4-Tetrahydrophenanthrene (1) was synthesized starting from [1,4-¹³C]-succinic acid. The mass spectral behavior (EI./MS., 70eV) of 1 is very similar to that of tetraline [2] concerning its loss of ethylene from the molecular ion. Similarly the fragmentation reaction of the synthetic precursors, ketones 7 and 8 , seems to partly undergo a carbon rearrangement reaction prior to the elimination of ethylene which is unlike to the behavior of α-tetralone.     

Die massenspektrometrische Retro-Diels-Alder-Reaktion: 1,2,3,4-Tetrahydrocarbazol. 30. Mitteilung über massenspektrometrische Untersuchungen

The mass spectral retro Diels-Alder-reaction: 1,2,3,4-tetrahydrocarbazole 1,2,3,4-Tetrahydrocarbazole undergoes a retro Diels-Alder-reaction under electron impact. C(2) and C(3) are eliminated as ethylene. This is shown by measuring the deuterated derivatives 1a , 1b and 1c . Furthermore the oxo-1,2,3,4-tetrahydrocarbazole derivatives 3 and 4 are investigated in respect to the mass spectral retro Diels-Alder reaction too.     

Neuartige massenspektrometrische Zerfallsreaktionen bei α,ω-disubstituierten Alkanen. 15. Mitteilung über das massenspektrometrische verhalten von stickstoffverbindungen [1]

The mass spectral behaviour of α,ω-disubstituted alkanes and, especially, that of different N-substituted α,ω-diaminoalkanes has been investigated. It was found that the two amino groups which are separated by CH₂-groups can fragment only to a small extent indepently from each other. Yet those fragmentation reactions are predominant in which both functional groups participate. The main reactions of this type are:

• 1 Loss of the N-substituent (R) from the molecular ion, leading to the [M⁺—R]-ions.
• 2 Loss of NH₃, primary or secondary amines from the [M⁺—R]-ion in the case of monodi-, tri- and tetra-substituted diamino compounds respectively.
• 3 α-Cleavage to the non charged nitrogen atom by forming the ions
• 4 S_Ni-type fragmentation.

The mechanisms of these fragmentation patterns were deduced by using D-labelled derivatives, from metastabile peaks and high resolution mass spectrometry. These reactions seem to be typical for disubstituted alkanes.     

Notiz zum massenspektrometrischen Zerfall monohalogenierter Essigsäuren und Essigsäureester. 36. Mitteilung über massenspektrometrische Untersuchungen

Note on the Mass Spectral Decomposition of Monohalogenated Acetic Acids and its Esters Besides the well known ester fragmentation reactions two unusual decomposition reactions are observed in the mass spectra of the title compounds, leading to the ions [M-CO₂]⁺ and [M-HX]⁺. The rearrangement reactions involved in the formation of these ions are discussed.     

Über die Bildung cyclischer Ionen und bicylischer Übergangszustände beim Zerfall substituierter α,ω-Alkandiamine im Massenspektrometer. 23. Mitteilung über das massenspektrometrische Verhalten von Stickstoffverbindungen

Formation of cyclic ions and bicyclic transition states in the mass spectral decomposition of substituted α,ω-alkanediamines. N-Phenethyl-N(4-acetamidobutyl)-p-toluene-sulfonamide ( 4 ) and its homologues were synthesized and the mass spectral behaviour investigated. After loss of a benzyl radical from the molecular ion two different fragmentation reactions are observed. The lower homologous members – namely compounds 1 , 2 and 3 – lose ketene by formation of cyclic ions (Scheme 1). The higher homologues of this series of compounds ( 4 , 5 , 6 ) show a pronounced (to 18% ∑₅₀) loss of p-toluene sulfonic acid. This decomposition reaction proceeds presumably through a bicyclic transition state (Scheme 3).     

Über in 6-Stellung basisch substituierte Morphanthridine. 8. Mitteilung über siebengliedrige Heterocyclen

Morphanthridines III with a basic substituent in position 6, which show neuroleptic activity, have been synthesised as follows: Chlorination of the lactams I with POCl₃ gave the iminochlorides II, which were converted by bases to the amidines III. The 11-oxo-morphanthridines VI and VII were synthesised using the same procedure, 2-(1-methylpiperazine-4-carbonyl)-2′-amino-benzophenone (XI) was obtained directly from the 6-chloro-11-oxo-morphanthridine (V) or by extended heating of VI with N-methylpiperazine. Reduction of the 11-oxo-compounds VI and VII with NaBH₄ gave the 11-hydroxy-compounds IX and X. 3-(2-aminophenyl)-phtalide (VIII) resulted from the acid hydrolysis of IX.