18515-11-2Relevant articles and documents
Sulfonation of a series of naphthalenes containing two different oxy substituents
Ansink, Harold R. W.,Zelvelder, Erwin,Cerfontain, Hans
, p. 216 - 225 (1993)
The reactions of a series of α,α- and β,β-disubstituted naphthalenes containing two different substituents OR1 (R1 = H, SO2CH3) and OR2 (R2 =CH3, SO2CH3) with sulfur trioxide in CD3NO2 has been studied.The electronic directing effect of the hydroxy group was found to be dominant over that of the methoxy group, which in turn dominates that of the mesyloxy group.Upon reaction with an excess of sulfur trioxide, the hydroxy group is, at least in part, sulfated.For the β-hydroxy-β-methoxynaphthalenes 3a-5a and for 3-mesyloxy-2-naphthol (3c) especially, hydrogen sulfate formation strongly influences the product mixture composition.Thus, upon reaction with 1.0 equiv of SO3, 7-methoxy-2-naphthol (5a) yields its 1-sulfonic acid (1-S), whereas upon reaction with 2.0 equiv, it is the 8-S that is mainly formed due to initial hydrogen sulfate formation.Furthermore, sulfonic acid isomerizations due to steric hindrance are observed.Upon using >2.0 equiv of SO3, formation of di- and trisulfonic acids, as well as sulfo derivatives of both 8,1-naphthalenesultone and the cyclic naphthalene-1-sulfonate-2-sulfate anhydride is observed.
Oxygen-Free Regioselective Biocatalytic Demethylation of Methyl-phenyl Ethers via Methyltransfer Employing Veratrol- O-demethylase
Grimm, Christopher,Lazzarotto, Mattia,Pompei, Simona,Schichler, Johanna,Richter, Nina,Farnberger, Judith E.,Fuchs, Michael,Kroutil, Wolfgang
, p. 10375 - 10380 (2020/10/02)
The cleavage of aryl methyl ethers is a common reaction in chemistry requiring rather harsh conditions; consequently, it is prone to undesired reactions and lacks regioselectivity. Nevertheless, O-demethylation of aryl methyl ethers is a tool to valorize natural and pharmaceutical compounds by deprotecting reactive hydroxyl moieties. Various oxidative enzymes are known to catalyze this reaction at the expense of molecular oxygen, which may lead in the case of phenols/catechols to undesired side reactions (e.g., oxidation, polymerization). Here an oxygen-independent demethylation via methyl transfer is presented employing a cobalamin-dependent veratrol-O-demethylase (vdmB). The biocatalytic demethylation transforms a variety of aryl methyl ethers with two functional methoxy moieties either in 1,2-position or in 1,3-position. Biocatalytic reactions enabled, for instance, the regioselective monodemethylation of substituted 3,4-dimethoxy phenol as well as the monodemethylation of 1,3,5-trimethoxybenzene. The methyltransferase vdmB was also successfully applied for the regioselective demethylation of natural compounds such as papaverine and rac-yatein. The approach presented here represents an alternative to chemical and enzymatic demethylation concepts and allows performing regioselective demethylation in the absence of oxygen under mild conditions, representing a valuable extension of the synthetic repertoire to modify pharmaceuticals and diversify natural products.
Enantioselective iron/bisquinolyldiamine ligand‐catalyzed oxidative coupling reaction of 2‐naphthols
Liu, Wen-Bo,Usman, Muhammad,Wu, Lin-Yang
, (2020/02/25)
An iron‐catalyzed asymmetric oxidative homo‐coupling of 2‐naphthols for the synthesis of 1,1′‐Bi‐2‐naphthol (BINOL) derivatives is reported. The coupling reaction provides enantioenriched BINOLs in good yields (up to 99%) and moderate enantioselectivities (up to 81:19 er) using an iron‐complex generated in situ from Fe(ClO4)2 and a bisquinolyldiamine ligand [(1R,2R)‐N1,N2‐di(quinolin‐8‐yl)cyclohexane‐1,2‐diamine, L1]. A number of ligands (L2–L8) and the analogs of L1, with various substituents and chiral backbones, were synthesized and examined in the oxidative coupling reactions.
