ABSTRACT
Dihydrobenzofuran is an important skeleton for bioactive compounds and natural products. Hydroquinones can be easily modified into substituted hydroquinones, which effectively undergo oxidation to produce the corresponding benzoquinone derivatives. Benzoquinones are reactive electrophiles that are frequently utilized in coupling with olefins to dihydrobenzofurans. Herein, we report the one-pot oxidative coupling of hydroquinones bearing an electron-withdrawing group at the C2 position with olefins to dihydrobenzofurans in the presence of the Lewis acidic FeCl3 and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) oxidant. Furthermore, this method was applied to the oxidative coupling of N-electron-withdrawing group-substituted 4-aminophenol.
Subject(s)
Alkenes , Benzofurans , Hydroquinones , Hydroquinones/chemistry , Hydroquinones/chemical synthesis , Benzofurans/chemistry , Benzofurans/chemical synthesis , Alkenes/chemistry , Molecular Structure , Oxidative Coupling , Ferric Compounds/chemistry , Oxidation-Reduction , Chlorides/chemistry , Benzoquinones/chemistry , Benzoquinones/chemical synthesisABSTRACT
The colorless solution of furan-2-yl bis(indolyl)methane (BIM) is newly revealed to work as a palladium (Pd2+) ion-selective chromogenic agent by turning orange. 5-(N-Methyl-N-phenyl-aminomethyl)-furan-2-yl BIM could be synthesized from 5-chloromethylfurfural as a biorenewable feedstock via one-pot and double functionalization, and a mixture of its solution and Pd2+ ions showed the highest absorbance at 465 nm in UV-Vis analysis. On the other hand, other metal ions (Cu2+, Cr2+, Cr3+, Fe2+, Fe3+, Ni2+, Zn2+, In2+, Pt2+, or Ce3+) exhibited no response.
ABSTRACT
Catechols possessing electron-withdrawing groups at the C3 position effectively underwent oxidative functionalization at the C4 position in the presence of phenyliodine(III) diacetate (PIDA) and heteroarene nucleophiles (e.g., indole, indazole, and benzotriazole) to produce the corresponding biaryl products. The PIDA-mediated oxidation of catechol derivatives afforded the ortho-benzoquinone intermediate, which subsequently underwent regioselective nucleophilic addition to the α,ß-unsaturated carbonyl moiety of ortho-benzoquinone using indole, indazole, and benzotriazole to give 4-substituted catechol derivatives in a one-pot manner. Notably, the nucleophilic substitution positions of indazole and benzotriazole were perfectly controlled. Additionally, the reaction using N-methylaniline as the nucleophile afforded a tertiary amine product.
