Electron impact mass spectrometry of 3-hydroxy-3,4,5,6-tetrahydro-2H-[1]benzoxocines. A comparison with the behaviour of isomeric 2-hydroxymethyl-2,3,4,5-tetrahydro-[1]-benzoxepines and 1,2-epoxy-5-(2-hydroxyphenyl)pentane

The mass spectrometric behavior of 3-methyl-3-hydroxybenzoxocines has been studied in detail by means of linked scans and mass analyzed ion kinetic energy spectrometry. The structure of the molecular ion and the fragmentation processes are strictly related to the structure of the neutral moieties. The possible isomerization of 3-hydroxy-10-methoxy-3-methyl-3,4,5,6-tetrahydro-2H-[1]benzoxocine to 2-methyl-2-[3-(3′-methoxy-2′-hydroxy)phenyl]pentyloxirane and to 2-hydroxymethyl-9-methoxy-2-methyl-2,3,4,5-tetrahydro[1]benzoxepine is investigated.     

Palladium(II) complexes with sulphonium ylides

Keto-stabilized sulphonium ylides displace styrene and benzonitrile from their adducts with PdCl₂ to give stable $\text{2}\text{1}$ ylidePdCl₂ complexes. Evidence is given for epimeric equilibrium between trans square-planar structures of these new complexes in solution.A $\text{1}\text{1}$ ylidePdI₂ complex, obtained from dimethylsulphonium methylide, is also described.     

Conversion of 2-(O-hydroxyphenyl) alkyl ketones into 2-hydroxymethylchroman derivatives

2-Hydroxymethylchromans are the only products arising from the oxidation by m-chloro-perbenzoic acid of the β-(o-hydroxyphenyl) olefins VI, obtained in turn form 2-(o-hydroxy-phenyl) alkyl ketones (I) by the Wittig olefination with triphenylphosphonium methylide.     

Electron impact mass spectrometry of some 2,3-dihydro-1-benzofuran-3-acetic acids

The mass spectrometric behaviour of four 2,3-dihydro-1-benzofuran-3-acetic acids has been studied in detail with the aid of exact mass measurements, linked scans, collisionally activated decomposition, mass analysed ion kinetic energy spectra and labelling experiments. Unusual fragmentation pathways are emphasized for which mechanisms are proposed.     

A comparison of electron impact mass spectrometry of isomeric pyranocoumarins (pyrano[3,2-c][1]benzopyran-5-ones) and pyranochromones (pyrano[2,3-b][1]benzopyran-5-ones)

The mass spectrometric behaviour of two pairs of isomeric 2,2-dimethylpyrano[3,2-c][1]benzopyran-5-ones (pyranocoumarins) and 2,2-dimethylpyrano[2,3-b][1]benzopyran-5-ones (pyranochromones) and four pairs of isomeric 2-hydroxymethyl-2-methylpyrano[3,2-c][1]benzopyran-5-ones (pyranocoumarins) and 2-hydroxymethyl-2-methylpyrano[2,3-b][1] benzopyran-5-ones (pyranochromones) has been studied in detail with the aid of exact mass measurements, linked scans, collisionally activated decompositions and deuterium labelling experiments. The presence in both series of compounds of the same ions derived by structural interconversion of both molecular ions is emphasized, and structural information on the ions [C₇H₅O₂]⁺ (m/z 121), highly characteristic for these classes of compounds, as for 4-hydroxycoumarins, is reported.     

Carbon-13 nuclear magnetic resonance studies of some phosphonium,arsonium, sulfonium and pyridinium keto-stabilized salts,and ylides and of their palladium(II) complexes

The ¹³C chemical shifts, the ¹³C³¹P coupling constants, and some one-bond ¹³C¹H coupling constants were measured for the title compounds. For the ylides of phosphorus, arsenic and sulfur, the data are consistent with an sp²-hybridized ylidic carbon with a strong, localized negative charge, while for the pyridinium ylide this charge is much more delocalized. in the homologous series of salts the electron-withdrawing ability of the groups studied varies in the order: Ph₃P⁺ < Ph₃As⁺ « Me₂S⁺ « Me₂C₅H₃N⁺. The differences in the carbonyl chemical shift between the ylides and the corresponding salts are a measure of the resonance stabilization of the negative charge in the form X⁺CCO^?; this stabilization varies with the groups studied in the order: Ph₃P⁺ < Ph₃As⁺ ≈ Me₂S⁺ « Me₂C₅H₃N⁺. The ylide—palladium(II) complexes contain a bond between the ylidic carbon and the metal: the ylidic carbon is shifted upfield in the complex with respect to the free ligand, while the adjacent carbonyl is shifted strongly downfield. These data suggest that the PdC(1) bond is strongly polarized with a high electron density on the C(1) atom which cannot be delocalized through resonance as in the free ligands.     

Electron impact mass spectrometry of 2-hydroxymethyl-3,4,5,6,7,8-hexahydro-2 H-1-benzopyran-5-ones. The unusual presence of [M?H3O]+ species in the fragmentation pattern of 4-phenyl derivatives

The mass spectrometric behaviour of some 2-hydroxymethyl-3,4,5,6,7,8-hexahydro-2H-1-benzopyran-5-ones is described and discussed with the aid of exact mass measurements, linked scans, labelling experiments and low electron energy measurements. The unusual presence of abundant [M? H₃O]⁺ species in the mass spectra of 4-phenyl substituted compounds is discussed in detail and a mechanism is proposed.     

The mass spectrometric isomerization of 1-benzoyl-2-(2′-hydroxy)phenylcyclopropane and 2-phenyl-2,3,4,5-tetrahydro-2,5-epoxy[1]-benzoxepin to a common structure

The mass spectrometric isomerization of 1-benzoyl-2-(2′-hydroxy)phenylcyclopropane and 2-phenyl-2,3,4,5-tetrahydro-2,5-epoxy[1]benzoxepin has been studied in detail with the aid of different ionization methods (electron impact, chemical ionization, field ionization, charge exchange) in conjunction with collisionally activated dissociation experiments.     

Electron impact mass spectrometry of polyannulated oxygen heterocycles with cyclic orthoester or acetal moieties

The mass spectrometric behaviour of the pairs of diastereoisomeric 3-methyl- and 3-phenyl-substituted 3,11b-epoxy-2,3,4,5,5a,11b-hexahydro-5a-hydroxyoxepino[3,2-c][1]benzopyran-6-ones 5,6 and 7,8 and the pairs of diastereoisomeric 3-methyl and 3-phenyl substituted 3,11a-epoxy-2,3,4,5,5a,11a-hexahydro-5a-hydroxyoxepino[2,3-b][1]benzopyran-6-ones 9,10 and 11,12 has been studied in detail with the aid of exact mass measurements, B/E linked scans, collisional experiments and deuterium labelling. Characteristic ionic species for angularly annulated compounds 5-8 and for linearly annulated ones 9-12 have been found, thus allowing the structural assignment. No differences could be determined in the fragmentation patterns of the diastereoisomeric compounds.