RhIII-catalyzed dual directing group assisted sterically hindered C-H bond activation: a unique route to meta and ortho substituted benzofurans was written by Yeh, Chien-Hung;Chen, Wei-Chen;Gandeepan, Parthasarathy;Hong, Ya-Chun;Shih, Cheng-Hung;Cheng, Chien-Hong. And the article was included in Organic & Biomolecular Chemistry in 2014.Quality Control of 3-Hydroxy-5-methoxybenzaldehyde This article mentions the following:
A new strategy for the synthesis of highly substituted benzofurans, e.g., I (X-rays single crystal structure shown), from meta-substituted hydroxybenzenes and alkynes via a rhodium(III)-catalyzed activation of a sterically hindered C-H bond is demonstrated. A possible mechanism involving dual directing group assisted ortho C-H bond activation is proposed. In the experiment, the researchers used many compounds, for example, 3-Hydroxy-5-methoxybenzaldehyde (cas: 57179-35-8Quality Control of 3-Hydroxy-5-methoxybenzaldehyde).
3-Hydroxy-5-methoxybenzaldehyde (cas: 57179-35-8) belongs to ethers. Relative to alcohols, ethers are generally less dense, are less soluble in water, and have lower boiling points. They are relatively unreactive, and as a result they are useful as solvents for fats, oils, waxes, perfumes, resins, dyes, gums, and hydrocarbons. Vapours of certain ethers are used as insecticides, miticides, and fumigants for soil. Ethers feature bent C–O–C linkages. In dimethyl ether, the bond angle is 111° and C–O distances are 141 pm. The barrier to rotation about the C–O bonds is low. The bonding of oxygen in ethers, alcohols, and water is similar. In the language of valence bond theory, the hybridization at oxygen is sp3.Quality Control of 3-Hydroxy-5-methoxybenzaldehyde
Referemce:
Ether – Wikipedia,
Ether | (C2H5)2O – PubChem