Curie-point pyrolysis products obtained from Val-Pro, Pro-Val, Ala-Pro, Pro-Ala, Gly-Ala, and Ala-Gly and their diketopiperazines (DKPs) were analysed by gas chromatography–mass spectrometry. The dipeptides readily formed corresponding DKPs by losing water molecules. The DKP in turn produced two to six primary products with an expulsion of simple molecules such as H2, propene, and CO. The products formed in low or trace amounts constitute secondary products. Bimolecular condensation to form products (17), (19), (23), (27), and (30) was also seen. The results showed that this can be a rapid method for characterising the structural features of these residues in complex systems.
J. Chem. Soc., Perkin Trans. 2

Smith, G. G., Reddy, G. S., & Boon, J. J. (1988). Gas chromatographic-mass spectrometric analysis of the Curie-point pyrolysis products of some dipeptides and their diketopiperazines. J. Chem. Soc., Perkin Trans. 2, 203–211. doi:10.1039/P29880000203