92157-61-4Relevant academic research and scientific papers
Synthesis of Lactams via Ir-Catalyzed C-H Amidation Involving Ir-Nitrene Intermediates
Li, Xiaoxun,Liu, Jitian,Tang, Weiping,Wang, Shuojin,Ye, Wenjing,Zheng, Junrong
, (2020/03/19)
x-membered lactams were synthesized via either an amidation of sp3 C-H bonds or an electrophilic substitution of arenes via Ir-nitrene intermediates. With the employment of a readily available iridium catalyst in dichloromethane or hexafluoro-2-propanol, a wide range of lactams were synthesized in good to excellent yields with high selectivity.
Understanding the regioselectivity in the oxidative condensation of catechins using pyrogallol-type model compounds
Yanase, Emiko,Ochiai, Yuto,Hirose, Sayumi
supporting information, p. 12359 - 12366 (2020/11/10)
Catechins are found in many foods, including tea. These compounds are bioactive. Previous studies have shown that catechins form dimers on oxidation, and there seem to be distinct regioselective effects. However, the dimerization mechanism and regioselectivity are not well understood. Therefore, we investigated the oxidation of four pyrogallol-type model compounds of epigallocatechin (EGC) having various substituents with 1 equiv of copper chloride and 30% dioxane in water. Compounds having 2C-2C or 2C-4C bonds in the B-ring were obtained in different product ratios. Comparison of the oxidation rates of each compound revealed that the model compounds having an oxygen atom corresponding to the 1-position of the C-ring of EGC underwent slow oxidation. In addition, using density functional theory calculations, we found that the highest occupied molecular orbital energies of these compounds were higher than those of the others. Further, the 2C-2C-bonded oxidation product having an A-ring and an oxygen atom at the C-ring 1-position was confirmed to have the highest thermodynamic stability. From these results, it is suggested that the regioselective condensation reaction of the catechin B-ring is related to interactions between the A-rings, as indicated by earlier studies, and the presence of oxygen at the 1-position of the C-ring in EGC.
Antioxidative properties of phenolic antioxidants isolated from corn steep liquor
Niwa, Toshio,Dpi, Umeyuki,Kato, Yoji,Osawa, Toshihiko
, p. 177 - 182 (2007/10/03)
With the immersion of corn into dilute sulfur oxide during starch-manufacturing processes, corn steep liquor (CSL) remains as leftover material. CSL is often used for fermentation, but its components are not fully understood. To determine the properties of CSL, 12 p-coumaric acid-related compounds were isolated from an ethyl acetate extract of CSL with the guidance of antioxidative activity on the rabbit erythrocyte membrane ghost system. The activity of these compounds was compared against oxidative damages, and it was elucidated that the activity of p-coumaric acid derivatives was mainly affected by their functional groups at the 3-position and less, by the conjugated side chain. Moreover, p-coumaric acid derivatives exhibited inhibitory activity stronger than that of tocopherols and ascorbic acid on peroxynitrite-mediated lipoprotein nitration. These findings that p-coumaric acid derivatives, which might play a beneficial role against oxidative damage, exist in CSL suggest this byproduct might be a useful resource of phenolic antioxidants.
