Mass spectrometric determination of new prostaglandin derivatives (series A and E)

The reaction of prostaglandins E1, E2, A1 and A2 with a 1:1 mixture of N,O-bis-trimethylsilyltrifluoroacetamide and piperidine favours the quantitative enolization of the 9-keto group of prostaglandins E, thus giving the corresponding tetrakis-TMS derivatives with molecular ions at m/e 642 and m/e 640 for prostaglandins E1 and E2, respectively, and also gives a new type of prostaglandin A-piperidyl-TMS derivative characterized by very strong base peaks at m/e 464 and 462, with molecular ions at m/e 637 and 635 for prostaglandins A1 and A2, respectively. The probable reaction mechanisms prevailing in both cases are discussed in accordance with the low and high resolution mass spectral data presented.