Oxidative Dearomatization of Phenols and Anilines via λ3- and λ5-Iodane-Mediated Phenylation and Oxygenation

Abstract

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.

Competitive Pseudopericyclic [3,3]- and [3,5]-Sigmatropic Rearrangements of Trichloroacetimidates

“…The 1 H NMR and 13 C NMR of 21 agreed with those reported in literature. 42,43 Synthesis of 1,2,4-Trimethyl-6-oxocyclohexa-2,4-dien-1-yl 2,2,2-trichloroacetimidate (22) and 5,7,7a-Trimethyl-2-(trichloromethyl)-3a,7a-dihydrobenzo[d]oxazol-3a-ol (23). To a suspension of sodium hydride (∼27 mg, 1.05 mmol, 95% w/w) in dry THF (3 mL) was added a solution of starting alcohol 21 (200 mg, 1.32 mmol) in dry THF (2 mL) at −20°C, and the mixture was allowed to stir at −20°C for about 30 min.…”

“…The [4 + 2]-Diels−Alder dimerization can be blocked merely by introducing a small alkyl or alkoxy substituent to the C-5 position of the 2,4-cyclohexadienone system. 42,43 Oxidative dearomatization of 2,3,5-trimethylphenol has been reported using SIBX as the oxidant, albeit in only 12% isolated yield of the desired alcohol 21. 43 The hydroxytrimethylcyclohexadienone 21 has also been prepared in modest (35%) yield by periodate oxidation.…”

“…42,43 Oxidative dearomatization of 2,3,5-trimethylphenol has been reported using SIBX as the oxidant, albeit in only 12% isolated yield of the desired alcohol 21. 43 The hydroxytrimethylcyclohexadienone 21 has also been prepared in modest (35%) yield by periodate oxidation. 42 In our hands, 21 was obtained in 40% yield (Scheme 8 and Figure 2a).…”

Efficient Synthesis of p-Quinols Using Catalytic Hypervalent Iodine Oxidation of 4-Arylphenols with 4-Iodophenoxyacetic Acid and Oxone

“…47) Oxidation with oiodylbenzoic acid (IBX) also occurred at the ortho position, reported respectively by Pettus' group 48) and Quideau's group. 49,50) These results strongly suggested that a trivalent iodine species is generated in situ by 3 and Oxone ® , it then oxidizes the phenols to produce p-quinols. Many reports in the literature have described oxidation of iodoarene with Oxone ® to give iodine(V) compound.…”

2‐Iodoxybenzoesäure – ein einfaches Oxidationsmittel mit einer Vielfalt an Anwendungsmöglichkeiten

“…Zwar ist berichtet, dass Iodbenzol durch Persäuren zu Iodoxybenzol oxidiert wird; [181] o-Iodbenzoesäure wird allerdings typischerweise nur bis zur Oxidationsstufe von o-Iodosylbenzoesäure (IBA) oxidiert. [40c, 182] Die Dearomatisierung von anderen aromatischen Systemen wie Anilinen [183] und Indolen [184] gelingt ebenfalls bei Verwendung von IBX. Porco et al zeigten, dass auch 2-Benzopyriliumsalze wie 146 durch IBX in 1,2-Dichlorethan-(DCE)/TFA oxidiert werden (Schema 48).…”