87-16-1

Usage

InChI:InChI=1/C14H12O4/c1-17-12-8-4-5-9-13(12)18-14(16)10-6-2-3-7-11(10)15/h2-9,15H,1H3

Upstream product

• 90-05-1 2-methoxy-phenol 
• 69-72-7 salicylic acid 
• 21905-73-7 2-carboxy-2'-methoxydiphenyl ether 
• 444-30-4 2-(trifluoromethyl)phenol 
• 79365-16-5 2-(2'-methoxyphenoxy)benzonitrile 

Downstream Products

• 55482-89-8 Guaiaspir 
• 1245937-10-3 C₁₇H₁₆O₄ 

Relevant academic research and scientific papers

Synthesis of salicylates from anionically activated aromatic trifluoromethyl group

An efficient approach to salicylates via a novel transformation of anionically activated aromatic trifluoromethyl group is described. Anionically activated trifluoromethyl group can react with phenols/alcohols under alkaline conditions to afford aryl/alkyl salicylates in high yields. Mechanism studies indicate that the carbonyl oxygen atom of ester is from the H2O in the solvent.

Cerium photocatalyzed radical smiles rearrangement of 2-aryloxybenzoic acids

We report herein a cerium photocatalyzed aryl migration from an aryl ether to a carboxylic acid group through radical-Smiles rearrangement. This operationally simple protocol utilizes inexpensive CeCl3as a photocatalyst and converted a variety of 2-aryloxybenzoic acids into aryl-2-hydroxybenzoates in good yields.

Efficient Aryl Migration from an Aryl Ether to a Carboxylic Acid Group To Form an Ester by Visible-Light Photoredox Catalysis

We have developed a highly efficient aryl migration from an aryl ether to a carboxylic acid group through retro-Smiles rearrangement by visible-light photoredox catalysis at ambient temperature. Transition metals and a stoichiometric oxidant and base are avoided in the transformation. Inspired by the high efficiency of this transformation and the fundamental importance of C?O bond cleavage, we developed a novel approach to the C?O cleavage of a biaryl ether to form two phenolic compounds, as demonstrated by a one-pot, two-step gram-scale reaction under mild conditions. The aryl migration exhibits broad scope and can be applied to the synthesis of pharmaceutical compounds, such as guacetisal. Primary mechanistic studies indicate that the catalytic cycle occurs by a reductive quenching pathway.

Preparation method for guacetisal

The invention discloses a preparation method for guacetisal. The preparation method comprises the following steps: with salicylic acid as a starting material, activating salicylic acid with N,N'-carbonyldiimidazole; then reacting activated salicylic acid with guaiacol so as to obtain guaiacol salicylate; and carrying out hydroxyacetylation so as to obtain guacetisal. The preparation method provided by the invention has the following advantages: the preparation method is formulated via improvement of conventional synthetic routes; the preparation method avoids usage of reagents with great toxicity and strong irritation, such as phosphorous oxychloride, thionyl chloride and phosgene; reaction temperature is substantially lowered; reaction conditions are mild; and the method is simple to operate. It is unexpectedly discovered in the invention that a novel crystal form of guacetisal is prepared by using the preparation method; and compared with conventional crystal forms, the novel crystal form improves the water-solubility and stability of guacetisal, allows the contents of related substances to be substantially reduced, and greatly improved medication security.

A photoredox-neutral Smiles rearrangement of 2-aryloxybenzoic acids

We report on the use of visible light photoredox catalysis for the radical Smiles rearrangement of 2-aryloxybenzoic acids to obtain aryl salicylates. The method is free of noble metals and operationally simple and the reaction can be run under mild batch or flow conditions. Being a redox neutral process, no stoichiometric oxidants or reductants are needed.

Carboxyl radical-assisted 1,5-aryl migration through Smiles rearrangement

We report herein, a silver(i)-catalyzed Smiles rearrangement of 2-aryloxy- or 2-(arylthio)benzoic acids to provide aryl-2-hydroxybenzoate or aryl-2-mercaptobenzoate dimer, respectively, through 1,5-aryl migration from oxygen or sulfur to carboxylate oxygen. Mechanistically, the aryl ether moiety undergoes an intramolecular ipso attack by the carboxyl radical followed by a C-O or C-S bond cleavage. Aryl-2-mercaptobenzoates undergo oxidative dimerization through a thiol moiety in situ.

Formation of dibenzofurans by flash vacuum pyrolysis of aryl 2-(allyloxy)benzoates and related reactions

Flash vacuum pyrolysis (FVP) of aryl 2-(allyloxy)benzoates 5 and of the corresponding aryl 2-(allylthio)benzoates 6 at 650°C, gives dibenzofurans 19 and dibenzothiophenes 20, respectively. The mechanism involves generation of phenoxyl (or thiophenoxyl) radicals by homolysis of the O-allyl (or S-allyl) bond, followed by ipso attack at the ester group, loss of CO2 and cyclisation of the resulting aryl radical. Synthetically, the procedure works well for p-substituted substrates, which lead to 2-substituted dibenzofurans 19b-f (73-90%) and dibenzothiophenes 20b-c (90-94%). Little selectivity is shown in the cyclisation of m-substituted substrates and competing interactions of the radical with the substituent - and ipso-attack - complicate the pyrolyses of o-substituted substrates. FVP of related radical precursors including 2-(allyloxy)phenyl benzoates 43 gave no dibenzofurans, whereas 2-(allyloxy-5-methyl)azobenzene 44 gave a much reduced yield. No carbazoles were obtained by FVP of 4-methylphenyl 2-(allylamino)benzoate 42.