The author of 《Recyclable nickel-catalyzed C-H/O-H dual functionalization of phenols with mandelic acids for the synthesis of 3-aryl benzofuran-2(3H)-ones under solvent-free conditions》 were Tang, Zhi; Tong, Zhou; Xu, Zhihui; Au, Chak-Tong; Qiu, Renhua; Yin, Shuang-Feng. And the article was published in Green Chemistry in 2019. Reference of 2-Hydroxy-2-(4-propoxyphenyl)acetic acid The author mentioned the following in the article:
Herein, a protocol was developed for the efficient synthesis of 3-aryl-benzofuran-2(3H)-ones I [R = H, 5-Me, 7-t-Bu, etc.; R1 = Ph, 4-HOC6H4, 2-ClC6H4, etc.] via C-H/O-H bond dual functionalization of phenols with mandelic acids under solvent-free conditions using Ni(OTf)2 as catalyst. The nickel catalyst could be easily recycled in a test of three runs at the scale of 10 mmol without significant decline in the product yield. It was demonstrated that the yield of the desired products could be increased, for example, in the synthesis of the antioxidant Irganox HP-136 to a scale of 166 g. In the experimental materials used by the author, we found 2-Hydroxy-2-(4-propoxyphenyl)acetic acid(cas: 79694-16-9Reference of 2-Hydroxy-2-(4-propoxyphenyl)acetic acid)
2-Hydroxy-2-(4-propoxyphenyl)acetic acid(cas: 79694-16-9) belongs to ethers.Oxygen is more electronegative than carbon, thus the alpha hydrogens of ethers are more acidic than those of simple hydrocarbons. Reference of 2-Hydroxy-2-(4-propoxyphenyl)acetic acid They are far less acidic than alpha hydrogens of carbonyl groups (such as in ketones or aldehydes), however.
Referemce:
Ether – Wikipedia,
Ether | (C2H5)2O – PubChem