Dimethylisopropylsilyl ether derivative in gas chromatography/mass spectrometry of 2,3-dinor-11-dehydrothromboxane B2

Abstract

The mass spectrum of the 2,Minor-1 ldehydrothromboxane B, (DNDTXB,) 1-methyl ester-1 l-n-propylamide-9,12,15-trisdimethylisopropylsilyl ether derivative was characterized by the base peak ion [ M -C,H,] + (m/z 670), and it exhibited a series of ions typical of the expected derivative. Many of the fragmentation products could be explained in terms of their simple bond fission mechanisms. Ions containing silicon atom in the low-mass region were produced via a six-membered ring transition or by formation of the cyclic dimethylsilylene ring system, which were common to the TXB metabolites having a Glactone ring system. These results revealed that this mass spectrum was similar to that of the corresponding lldehydro-TXB, derivative except for the obvious shift produced by the lack of C2/C3 hydrocarbon units. The presence of DNDTXB, in the urine of a healthy adult was confirmed by gas chromatography/selected ion monitoring.

Mass Spectrometric Fragmentation of Trimethylsilyl and Related Alkylsilyl Derivatives

“…An extensive study of the fragmentation of 11‐dehydrothromboxane B 2 ( 239 ) (Ishibashi et al, ; ) and 2,3‐di‐nor‐11‐dehydrothromboxane B 2 ( 240 ) (Ishibashi et al, ) as their tri‐( iso ‐Pr‐Si(CH 3 ) 2 )‐ n ‐propylamide methyl ester derivatives has been made by Ishibashi et al As well as the [M − 43] + , α‐cleavage ions and ions formed by losses of i PDMS‐OH, several fragments of the [M − 43] + ion involving bonding to oxygen were prominent as were fragments formed by internal bonding of intact silyl groups in a similar manner to that of the diethylsilyl derivatives discussed below.…”