[reaction: see text] SIBX is a nonexplosive formulation of IBX that can be used as a suspension in a variety of standard organic solvents such as refluxing EtOAc and THF to oxidize safely alcohols into aldehydes and ketones. The use of hot THF is limited to the oxidation of allylic and benzylic alcohols. Most yields are comparable to those obtained with IBX or DMP. SIBX can also be used to perform oxygenative demethylation of 2-methoxyarenols into orthoquinones and catechols.
A series of 2-methoxy and 2-methylphenols have been submitted to oxygenative oxidation reactions using (1) the λ 3 -iodane DIB, (2) a non-explosive and non-moisture sensitive version of the λ 5 -iodane IBX, named SIBX for Stabilized IBX, and (3) anodic oxidation with the aim of identifying the best reaction conditions for preparing orthoquinonoid cyclohexadienone synthons. Both the use of DIB and anodic oxidation appeared equally valuable for making orthoquinone dimethyl ketals, but the λ 3 -and λ
5-iodane reagents are more appropriate to induce ortho-oxygenation of 2-methylphenols. In particular, SIBX emerged as a useful reagent for mediating ortho-hydroxylation into dimerizing orthoquinols, a tactic that can be applied to the synthesis of natural bis(monoterpenoids) such as aquaticol.
Treatment of 2-methylphenols with chloro(diphenyl)-λ3-iodane led to their regioselective dearomatizing 2-phenylation into cyclohexa-2,4-dienone derivatives via a proposed ligand coupling reaction. In the same vein of investigation, treatment of 2-methylanilines with the λ5-iodane 2-iodoxybenzoic acid IBX reagent led to their regioselective dearomatization into previously undescribed ortho-quinol imines.
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