Synthesis of sterically shielded piperidine nitroxides via acid-catalyzed heterocyclization of β-aminoketone derivatives with ketones

• Mark M. Gulman,
• Yurii I. Glazachev and
• Sergey A. Dobrynin

Beilstein J. Org. Chem. 2026, 22, 948–954, doi:10.3762/bjoc.22.74

• -tetraethylpiperidine (TEEPONE). Keywords: heterocyclization; piperidine nitroxide; TEEPONE synthesis; Introduction Since their discovery in 1959 by Lebedev and Kazarnovsky, stable nitroxides of the piperidine series (2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) derivatives) hold a prominent position as compounds of

• of nitroxides and increases their lifetimes in biological systems [12], which makes these radicals promising MRI contrast agents [13], spin probes for in vivo EPRI [14][15] and antioxidant tissue protectors [16]. Existing methods for the synthesis of such sterically hindered piperidine nitroxide