High resolution mass spectrometric studies of some bicyclic γ‐lactones

Abstract

The mass spectra of three bicyclic y-lactones have been studied, and the fragmentation pathways have been proposed with the aid of accurate mass measurements and metastable transitions. An unusually low [M -CH,] ion and the presence of an abundant [M -C,H,] ion in the mass spectrum of dihydroactinidiolide u ere interpreted as a possible rearrangement involving a methyl migration. The eliminations of methyl radical, carbon monoxide and ketene are important processes in many cases.

Growth inhibitors from spikerush

“…The search for phytotoxic substances in spikerush (.Eleocharis coloradoensis) has been guided at every stage by biological assay which allows the separation of active compounds (often missed by the more classical approach) from the more abundant components or those easily separated. Figure 2 summarizes the isolation of an active fraction which was 73% of a single component tentatively identified as dihydroactinidiolide (I) by mass spectral analyses (Chen et al, 1970). Because adequate amounts were unavailable for biological testing and its similarity to patulin (V), a known phytotoxic compound (Jefferys, 1952), dihydroactinidiolide was synthesized to confirm its identity and determine its biological activity.…”

“…The mother liquor was vacuum transferred at 1 mm pressure and 50 °C to give, by GC, a compound of about 73% purity. Mass spectral analysis suggested the butenolide I (Figure 1), i.e., dihydroactinidiolide (Chen et al, 1970, firmed by its NMR spectrum (CDC13): 1.19 (3 H, s), 1.22 (3 H, s), 1.50 (3 H, s), 5.59 (1 H, s); IR spectrum (neat): 1752 cm"1; UV spectrum: \maiEt0H 212 (18000).…”

In vitro acetylcholinesterase inhibitory activity and chemical composition of the dichloromethane extracts of the leaves and inflorescences of the tumbleweed, Trachyandra laxa (N.E.Br.) Oberm. var. rigida (Suesseng.) Roessl

“…ion and hence it may be inferred that compound 4 is a hydroxylated analogue of DHA (3). The ion observed at m/z 163 will then correspond to a [M -CH 3 -H 2 O] + ion, while the base peak, observed at m/z 135, will then be formed by the loss of CO from the ion observed at m/z 163 (Chen et al, 1970). The RI of compound 4 was experimentally determined to be 1751.…”

Characterization of the Dissociation Behavior of Gas-Phase Protonated and Methylated Lactones

“…Mass spectrometric studies of lactones generally have been limited to characterization of the fragmentation behavior of lactones upon electron ionization (El) [12][13][14][15][16] . For example, Mcfadden et al [U) studied the effect of increasing aliphatic sid e chain length on the EI mass spectra of a series of lactones.…”