Study of 1-hydroxybenzotriazole/benzotriazole N-oxide tautomerism in the gas phase by photoelectron spectroscopy

Barriers to the intramolecular N‐ to N‐transfer of different groups in pyrazoles: Prototropy vs. Elementotropy

“…However, although NH-pyrazoles rapidly attain the equilibrium in the gas phase (the tautomeric equilibrium constant, K T , changes monotonically with temperature), theoretical studies have shown that the transfer is not intramolecular but must involve collisions with other molecules or the walls on the instrument of measure [3, 24,25]. The other substituents have been much less studied to the point that for some people tautomerism is synonymous with prototropy.…”

1H, 13C and 15N NMR spectroscopy and tautomerism of nitrobenzotriazoles

“…[31] The benzotriazole N-oxide −−− −−− 1-hydroxybenzotriazole equilibrium, investigated by photoelectron spectroscopy, proved the presence of the only 1-hydroxybenzotriazole in the gas-phase (Scheme 3). [32] According to 15 N NMR spectroscopy the content of the N-hydroxy tautomer in both equilibrium mixtures, Noxide −−− −−− 1-hydroxybenzotriazole [33] and N-oxide −−− −−− 1-hydroxybenzimidazole, [34] is significantly higher than that of the N-oxide form and is proportional to the pK a value of the solvent employed. The latter is in good accordance with electron spectroscopy data.…”

Nucleofuge Generating Glycosidations by the Remote Activation of Hydroxybenzotriazolyl Glycosides

“…Hydrolysis of HOBt glycoside was noticed to afford the corresponding hemiacetal and trace amount of ROTf if the Tf 2 O was introduced prior to the addition of acceptor ROH. Equilibration of species D to HOBt ( 1 ) is important because it makes the leaving group a noncompeting nucleophile. − Minute variation in reaction time was observed with individual anomers of the donor 4 without any significance on the net stereochemical outcome of the disaccharide 6 . The regeneration of the nucleofuge was further investigated by UPLC-MS studies (Figure ).…”