Functionalization of sterically hindered catechol and o-benzoquinone with 2,2,6,6-tetramethylpiperidine 1-oxyl

Sterically hindered 4,6-di- tert -butyl-3-formylcatechol and 3,6-di- tert -butyl- o -benzoquinone react with 4-amino-2,2,6,6-tetramethylpiperidine 1-oxyl to give new chelate ligands of the o -quinone type bearing a 2,2,6,6-tetramethylpiperidine 1-oxyl neutral radical moiety. Structures of the synthesized compounds were established by ESR spectroscopy, IR spectroscopy, mass spectrometry, and X-ray diffraction analysis.