Solvent-controlled selective synthesis of biphenols and quinones via oxidative coupling of phenols

Abstract

A regioselective synthesis of unsymmetrical and symmetrical biphenols and binaphthols via oxidative coupling of phenols or naphthols in the presence of KSO in CFCOOH under ambient conditions is described. Interestingly, the 1 : 1 ratio of HO and CHCN solvent mixtures at 80 °C instead of CFCOOH provided substituted unsymmetrical quinones. A gram-scale synthesis of biphenols and binaphthols was demonstrated.

Electrocatalytic Synthesis of Non‐Symmetric Biphenols Mediated by Tri(p‐bromophenyl)amine: Selective Oxidative Cross‐Coupling of Different Phenols and Naphthols

“…[5] Right recently, K 2 S 2 O 8 in CF 3 COOH has also been employed to realize the cross-coupling of phenol-phenol or phenolnaphthol in the presence of Bu 4 NHSO 3 (10 mol%). [6] Moreover, Kita and coworkers have developed an organo-iodine(III)-catalyzed oxidative cross-coupling reaction of phenol-phenol using oxone as the terminal oxidant in HFIP solvent. [7] In spite of these progresses, expensive transition-metal catalysts, such as Fe[TPP]Cl, and excess terminal oxidant are required, which leads to producing large amount of waste (Scheme 1a).…”

“…[6] Yellow liquid; 1 4, 107.5, 117.2, 121.1, 123.3, 124.7, 126.6, 128.1, 128.9, 129.5, 133.5, 134.8, 148.0, 150.4. 1-(4-Hydroxy-3,5-dimethoxyphenyl)naphthalene-2,3-diol (3b). [6] Yellow liquid; 1 H NMR (400 MHz, CDCl 3 ) δ: 3.75 (s, 6H), 6.52 (s, 2H), 7.10 (d, J = 7.6 Hz, 1H), 7.13-7.20 (m, 2H), 7.31 (d, J = 8.0 Hz, 1H), 7.62 (d, J = 8.0 Hz, 1H); 13 C NMR (100 MHz, DMSO-d 6 ) δ: 56. 5, 108.7, 123.0, 123.3, 124.7, 126.3, 126.6, 128.8, 129.0, 135.0, 144.0, 146.6, 148.3.…”

“…1-(4-Hydroxy-3,5-dimethoxyphenyl)naphthalene-2,7-diol (3c). [6] 107.5, 114.7, 115.1, 119.8, 124.2, 125.0, 129.3, 129.9, 134.6, 135.1, 147.9, 150.9, 154.6. 1-(2-Hydroxy-4,5-dimethoxyphenyl) naphthalene-2,3-diol (3d).…”

“…8, 55.7, 106.6, 111.7, 114.6, 114.7, 114.9, 118.9, 123.8, 124.2, 129.4, 129.8, 130.1, 134.2, 141.3, 146.9, 151.1, 153.9;IR (KBr) ν: 1461, 1492, 1513, 1624, 1698, 2850, 2919 5, 115.8, 117.9, 118.0, 118.4, 122.6, 123.6, 124.5, 126.9, 128.2, 129.2, 130.2, 133.3, 146.5, 151.2, 154.1 6-Bromo-1-(4-hydroxy-3,5-dimethoxyphenyl) , 115.8, 120.0, 122.3, 125.9, 127.3, 128.0, 129.3, 129.5, 129.9, 133.0, 135.2, 148.4 × 2, 152.7. 1,4-Bis(4-hydroxy-3,5-dimethoxyphenyl)naphthalene-2,3diol (4a). [6] 7, 102.7, 117.0, 119.4, 120.2, 120.4, 123.8, 130.0, 136.0, 143. 1, 56.1, 56.3, 56.4, 106.2, 112.7, 116.0, 126.8, 132.8, 133.5, 134.9, 143.2, 145.5, 146.6. 3 ',5'-Dimethoxy-5-methyl-[1,1'-biphenyl]-2,4'-diol (5b).…”

Selective Formation of 4,4′‐Biphenols by Anodic Dehydrogenative Cross‐ and Homo‐Coupling Reaction

“…[1b] This leads to al imited tolerance of variousf unctional groups.A nother approach is the direct CÀHa ctivation by the means of chemical oxidizerst o create the desired arylic CÀCb ond (Scheme 1). [10] Recently,K ita and co-workers reported an organo-iodine(III)-catalyzed pathway to access the desired cross-coupling products. [11] Unfortunately,this method is very tedious and needs Oxone as at erminal oxidant.…”