Department of Nutritional and Food Sciences, Molecular Food Technology, University of Bonn, Friedrich-Hirzebruch-Allee 7, D-53115 Bonn, Germany.
Molecules. 2021 Mar 3;26(5):1342. doi: 10.3390/molecules26051342.
The approach presented in this study is the first for the hemisynthesis of methylated anthocyanins. It was possible to obtain cyanidin-3--glucoside derivatives with different degrees of methylation. Cautious identification of 4'-, 5-, and 7-OH monomethylated derivatives was also accomplished. The methylation agent used was the "green chemical" dimethyl carbonate (DMC), which is characterized by low human and ecological toxicity. The influence of the temperature, reaction time, and amount of the required diazabicyclo[5.4.0]undec-7-en (DBU) catalyst on the formation of the products was examined. Compared to conventional synthesis methods for methylated flavonoids using DMC and DBU, the conditions identified in this study result in a reduction of reaction time, and an important side reaction, so-called carboxymethylation, was minimized by using higher amounts of catalyst.
本研究提出的方法是半合成甲基化花色苷的首例。我们成功获得了不同程度甲基化的矢车菊素-3-O-葡萄糖苷衍生物。同时还谨慎鉴定了 4'-、5-和 7-OH 单甲基化衍生物。所用的甲基化试剂是“绿色化学”试剂碳酸二甲酯（DMC），其具有低毒性和低生态毒性的特点。我们考察了温度、反应时间和所需的 1,8-二氮杂双环[5.4.0]十一碳-7-烯（DBU）催化剂用量对产物形成的影响。与使用 DMC 和 DBU 的常规合成方法相比，本研究中确定的条件可以缩短反应时间，通过使用更多量的催化剂，重要的副反应，即所谓的羧甲基化反应，可以最小化。
