Mass spectrometric study of 2-keto(thio)tetrahydropyrimidine derivatives

The fragmentation pathways of 2-keto(thio)-6-methyl-5-carbethoxy(acetyl)-4-aryl-1,2,3,4-tetrahydropyrimidines were established using high resolution mass spectra and DADI spectra. An unusual rearrangement was observed, which involves cyclization of the aryl substituent in the 4 position with the oxygen of an ester group and elimination of a C2H5 radical. © 1989 Plenum Publishing Corporation.