Spectres de Masse de la Methyl‐2 Thiazolidinethione‐2 et de la Dimethyl‐2,4 Δ₂‐Thiazoline

Abstract

The mass spectra of the title compounds point to rupture of S-C-2 and N-C-4 bonds as being the dominant reaction under electron impact. I3C labelling of a selected position of the ring allows some fragmentation pathways to be confirmed.

Electron ionisation mass spectral studies of bridgehead‐fused Δ2‐norbornanethiazolines

“…1). The conclusions derived from this study, in combination with earlier studies reported about the behaviour under EI of other norbornane derivatives 9-21 and simple thiazolines, [22][23][24][25] constitute an interesting contribution in order to facilitate the mass spectral characterisation of this interesting class of chiral ligands with no precedents in the literature.…”

“…Losses of nitrile give rise to characteristic ions in the fragmentation patterns of other previously described thiazolines, thiazoles and related compounds. [22][23][24][25][26][27][28] The precursor ion scan spectra of 14, recorded from compounds 3 and 6, indicate connectivity between this ion and 9. Therefore, the main pathway for the formation of protonated nitrile 14 involves 1,3-hydrogen rearrangement from the C(5) methyl group to the nitrogen atom, as occurs in the case of 2,4-dimethyl-D 2 -thiazoline, 23 followed by subsequent heterolytic cleavage of C(3)-S and C(5)-N bonds (Scheme 1).…”

“…[22][23][24][25][26][27][28] The precursor ion scan spectra of 14, recorded from compounds 3 and 6, indicate connectivity between this ion and 9. Therefore, the main pathway for the formation of protonated nitrile 14 involves 1,3-hydrogen rearrangement from the C(5) methyl group to the nitrogen atom, as occurs in the case of 2,4-dimethyl-D 2 -thiazoline, 23 followed by subsequent heterolytic cleavage of C(3)-S and C(5)-N bonds (Scheme 1). Similar [RCNH] þ ions have also been detected in the EI spectra of 2-thiazolin-4-one derivatives 25 and thiazole derivatives in which a hydrogen rearrangement to the endocyclic nitrogen is possible.…”

1,3‐Dipolar Cycloreversions

“…18, 721-738 (2979) sion. However, the diazoalkane/cyclopropene adducts (70) are relatively stable and their cycloreversion properties depend largely on the ~u b s t i t u e n t s [~~~'~~'~~~ '32.1331. For instance, while compound (70a) cycloreverts smoothly at 80 0C[132c1, (706) undergoes cycloreversion at 0 "C and could not be isolated["'"].…”

“…By contrast, in the thermolytic fragmentation of (73) and (74) Thermolysis and photolysis of (708 and (70g) are stereospecific reactions initiated by a cycloreversion mechan i~m [~~J . Schneider et al recently showed that the cycloreversion mechanism may be the sole photochemical and thermal fragmentation route for 2,3-diazabicyclo[3.1.0]hex-2-enes (70) [1331. The authors were able to demonstrate that diazoalkane (75) is the sole primary product of (70h) on photochemical (and most probably also on thermal) treatment by trap-Angew. Chem.…”