Mass spectrometry and pyrolytic decomposition of 2-amino-3′,4′,6-trisubstituted isoflavones

The 2-aminoisoflavones studied exhibited some familiar fragmentation pathways, such as the formation of the retro-Diels–Alder ions. However, substitutions at C(2), C(3′), C(4′) and C(6) induced some specific decompositions of both mass spectrometric and pyrolytic origin. Pyrolytic decompositions reverse to the Mannich reaction occurred with all compounds to variable extents. The three compounds with the (Me)₂NSO₂ substitution at C(6) exhibited another type of pyrolytic reaction, namely the formation of products corresponding to ions of m/z 272, 300 and 314, depending on the type of substitution at C(3′). The occurrence of an interesting ‘ortho effect’, the elimination of the elements of CH₃O from C(3′) and C(4′), was also established.