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Intermolecular O ‐methylation during EIMS of quaternary methoiodides of isoquinoline alkaloids
Author(s) -
Huang ZhiHeng,
Zhu JiPing,
Zhou YunLi
Publication year - 1984
Publication title -
organic mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0030-493X
DOI - 10.1002/oms.1210191204
Subject(s) - isoquinoline , chemistry , methylation , intermolecular force , stereochemistry , mass spectrum , tetrahydropalmatine , ion , molecule , organic chemistry , biochemistry , medicine , alternative medicine , traditional chinese medicine , pathology , corydalis , gene
Quaternary methoiodides of tetrahydroprotoberberine (THB) alkaloids (1‐8) tend to undergo preionization degradation in the mass spectrometer at elevated temperatures. Different reaction pathways have been found in relation to the structure of the substance studied. Permethylated alkaloids, e.g. tetrahydropalmatine‐CH 3 I (8), give predominantly the Hofmann degradation intermediates and the fragment ions derived therein, while the alkaloids with free phenolic group(groups), as exemplified by scoulerine‐CH 3 I (1), show a greater tendency to be methylated by an intermolecular CH 3 transfer mechanism:The latter process has been systematically studied and the mechanism substantiated through comparison of the spectra of analogous series, B / E linked scan and CD 3 labelling. Similar behaviour has been observed in bisbenzyltetrahydroisoquinoline alkaloids.