Mass spectrometric analysis of 1,2,4‐Oxadiazoles and 4,5‐Dihydro‐1,2,4‐Oxadiazoles

Abstract

1,2,4-Oxadiazoles and 4,5-dihydro-1,2,4-oxadiazoles are an interesting class of compounds because of their pharmacological and other properties. Although short descriptions of these compounds under mass spectrometric conditions exist, we thought it worthwhile to write a comprehensive review of this class of compounds. Therefore, this revision deals first with 1,2,4-oxadiazoles and then 4,5-dihydro-1,2,4-oxadiazoles from 1964 until the year 2002. Much work on these compounds has been described under electron impact conditions and only a little under chemical ionization (CI).

Characterization of Isomeric 1,2,4-Oxadiazolyl-N-Methylpyridinium Salts by Electrospray Ionization Tandem Mass Spectrometry

“…This RCA fragmentation is typical of 1,2,4-oxadiazole systems subjected to electron impact ionization. [33][34][35] The peak at m/z 119 can be assigned to a fragmentation which yields an oxazirine and a nitrile fragment (path b in Scheme 1). The lower relative abundance of the peak at Figure 1(d)], has been observed.…”

Oxadiazoles

“…A recent review reports a detailed mass spectrometric analysis of a series of 1,2,4-oxadiazoles and 4,5-dihydro-1,2,4-oxadiazoles [177]. The fragmentation mode of the latter compounds differs from that of 1,2,4-oxadiazoles.…”

Facile Synthesis of Tricyclic 1,2,4-Oxadiazolines-Fused Tetrahydro-Isoquinolines from Oxime Chlorides with 3,4-Dihydroisoquinoline Imines

“…The 1,2,4-oxadiazole ring is an important structural motif, but also considered a privileged building block in a variety of medicinal molecules and biologically active compounds [ 1 , 2 , 3 , 4 ]. Notably, various functionalized 1,2,4-oxadiazole derivatives possess a wide range of pharmacological and biological activities, such as anticancer, antimicrobial, antiviral, anti-Alzheimer’s disease, and antibacterial activities.…”