Mass spectra of selected beta‐carbolines [β‐9H‐pyrido(3,4‐b)indoles]

Abstract

The mass spectra of fifteen B-carbolines have been interpreted and proposed fragmentations have been substantiated by means of deuterium-labeling and accurate mass determinations. Most decompositions were predictable. An interesting fragmentation was observed in the spectra of 1 -alkyl-l,2,3,4-tetrahydro-~-carbolines, which rearrange to expel an alkylamino (RNH) radical from the molecular ion. 157 230-20 -

Analytical characterisation of the routes by thermolytic decarboxylation from tryptophan to tryptamine using ketone catalysts, resulting in tetrahydro-β-carboline formation

“…A cleavage of a methyl radical however, was observed to a minor extent also, leading to the formation of m/z 199 (3, 12%) and m/z 213 (5, 17%), respectively. The observation of alkyl-cleavages was consistent with Coutts et al [33] and Gynther [31] who reported on the EI mass spectra of several 1-monosubstituted-THBCs. 1-Ethyl-monosubstituted-THBCs have also been reported to show a dominating C 2 H 5 radical cleavage [34].…”

Synthesis and isolation of nitro‐bT‐carbolines obtained by nitration of commercial β‐carboline alkaloids

“…After the expulsion of the nitro subtituent the main fragmentation path of 1a, 1b, 2a, 2b, 3a, 3b, 5a and 5b are Sep-Oct 2001Vol. 38 (8) 62 (2) similar to those described for the corresponding β-carboline [12,62]. Finally, although very clear ei-ms spectra have been reported for dinitroaromatic compounds, e.g., dinitrocarbazoles [61], (see in Table 3 ei-ms data for 1,6-dinitro and 3,6-dinitrocarbazole, compounds 6c and 6d, respectivley), peaks of very low intensity were obtained from the dinitro derivatives of harmine (Table 3, compound 3c) by ei-ms even at very soft experimental conditions (low temperature at the injection chamber; low voltage for the ionizing electron source).…”

N,N-Dimethyltryptamine and dichloromethane: Rearrangement of quaternary ammonium salt product during GC–EI and CI-MS–MS analysis

“…If this was the case, the dominating mechanism, i.e. base peak formation, would then be represented by alkyl cleavages [20][21][22][23]. CI-MS-MS confirmed the [M + H] + to occur at m/z 187 with further dissociation to m/z 144.…”

“…2(C1 and C2), respectively. Under EI conditions, a characteristic base peak at m/z 143 was observed which is known to occur after retro-Diels-Alder fragmentation (RDA) [20]. The presence of this base peak ion can also provide some structural information because it points towards the absence of any substituent at position C-1.…”