Some 2-nitromethyl-, 2,6-bis(nitromethyl)-, 2-cyano-, and 2,6-dicyano-substituted derivatives of polyalkylated 3,5-dicyano-1,4-dihydropyridines

Abstract

Nitration of polyalkyated 3,5-dicyano-1,4-dihydropyridines Ia-Id to the first and second degrees has been studied leading to compounds II and III, and conversion of nitromethyl groups of these compounds into nitrile groups with formation of tricyano derivatives IV and tetracyano derivatives V has been followed. Also given is the fragmentation of the synthesized compounds II-V by an electron impact in mass spectrometer and further spectral characteristics.

Mass spectra of new substituted 2-amino-4H-pyrans: a retro-Diels-Alder reaction pattern

“…Therefore, suitably functionalized 4 H ‐pyrans have been recently developed in our laboratory in the search for biologically active compounds 2. In contrast to the many mass spectral studies carried out on 1,4‐DHP compounds,3–5 detailed studies of fragmentation patterns on the 4 H ‐pyran system have not yet become common, and most of the reported mass spectral measurements have been used to establish the parent molecular mass 6. Although the 4 H ‐pyran framework is scarcely found in biologically active compounds due to its instability, a good understanding of the mass spectrometric fragmentation modes is of interest in order to determine the structural parameters which define its stability.…”

An overview of the retro-Diels-Alder reaction in semiunsaturated heterocyclic rings: mass spectra of new substituted 1,4,5,6,7,8-hexahydroquinolines and their oxo-analogues 5,6,7,8-tetrahydro-4H-chromenes

“…We wish to report here a comparative spectrometric study of hexahydroquinolines and 4 H ‐chromenes, in order to determine their similarities and differences. Despite the literature examples of the mass spectra of 1,4‐DHPs,7–13 only a few examples of the spectrometric behaviour of 4 H ‐pyrans are documented 14–16. Due to synthetic difficulties in preparing hexahydroquinolines and 4 H ‐chromenes with similar substituents, a detailed comparative investigation of these systems has not yet been accomplished.…”