Reaction of 3,6-di-tert-butyl-o-benzoquinone with dimedone. Functionalized derivatives of hinderedo-quinones and catechols

Abstract

The reaction of 3,6-di-tert-butyl-o-benzoquinone with dimedone in the presence of a catalytic amount of Et3N occurs as repeated 1,4-nucleophilic addition--oxidation and isomerization of a tricyclic quinone into qulnomethane. The intermediate products were isolated and characterized. Semiquinone complexes of quinones were studied by ESR in solution.

Alkylation of Catechol with Benzhydrol: Unusual Regioselectivity in the Synthesis of o‐Quinones and Catechols

“…In fact, quinone‐methide form 4 appears more stable than the 3,5‐disubstituted derivative due to its p ‐quinoid structure; compound 3 c completely and irreversibly rearranges into 4 at room temperature in solution. It should be mentioned that similar behavior was observed previously in the case of o ‐quinones that are capable of rearrangement into a quinone‐methide form 8. 9…”

“…It should be mentioned that similar behavior was observed previously in the case of o ‐quinones that are capable of rearrangement into a quinone‐methide form 8. 9…”

Functionalization of sterically hindered o-benzoquinones: amino-substituted 3,6-di(tert-butyl)-o-benzoquinones

“…The formation of paramagnetic complexes was de tected in the reactions of o quinones with Mn 2 (CO) 10 performed under visible light irradiation in toluene (Scheme 4). The ESR spectra of chelate o semiquinone manganese tetracarbonyl complexes 2a-c show the hyperfine coupling of the unpaired electron with mag netic isotopes of one manganese atom ( 55 Mn, I = 5/2, 100% (see Ref.…”

Annulation of a 1,3-dithiole ring to a sterically hindered o-quinone core. Novel ditopic redox-active ligands

“…Due to the reversibility of dithiocarboxylation, the reaction mixture contains some amount of sodium acetylacetonate, which can attack the chlorine atom at the backbone of 2 to give the substitution product ( Scheme 2 ). According to the reported data, the quinone-methide form is more preferable for such species than the o -quinone one [ 37 ]. After the first step, the remaining chlorine atom in the molecule could not be a subject for attack from another molecule of sodium acetylacetonate since it is shielded by neighboring groups, but it could be substituted with the less bulky sulfur-containing group.…”