Comparison of the Mass Spectra of 6-Thiotheophyllines and 6-Sulfinyltheophyllines

Article abstract of DOI:10.1002/oms.1210171107

Under electron impact, 6-thiotheophyllines eliminate various fragments from the pyrimidine moiety.In a retro Diels-Alder reaction, they lose the fragment X=C=NCH3 from positions 1 and 2 of the pyrimidine ring.In 6-sulfinyltheophyllines, the sulfinyl group is the main target for fragmentation; it can lose either oxygen or sulfur, and the abundance of ⁺ and ⁺ is much higher than the abundance of the molecular ion.Elimination of the sufur atom of the 6-sulfinyl substituent, with retention of its oxygen, may be explained by intermediate formation of a <*> ring.All further fragmentation of the 6-sulfinyl derivatives proceed by a primary loss of oxygen or sulfur, followed by elimination of fragments from the pyrimidine moiety, similar to the primary processes, observed in the mass spectra of the 6-thiotheophyllines.