School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan.
Department of Chemistry, Faculty of Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, 060-0810, Japan.
Org Lett. 2020 Sep 4;22(17):6729-6733. doi: 10.1021/acs.orglett.0c02066. Epub 2020 Aug 26.
Herein, a practical synthesis of the macaranoyl group contained in ellagitannins, i.e., a C-O digallate structure with a tetra--substituted diaryl ether bond, is described. The methodology involved an oxa-Michael addition/elimination reaction between a brominated -quinone monoketal and a phenol with a hexahydroxydiphenoyl moiety in the presence of 18-crown-6 under dark conditions, followed by reductive aromatization. The existence of rotamers originating from the constructed ether moiety is discussed as well.
本文描述了鞣花单宁中麦拉丹酰基（macaranoyl group）的实用合成方法，即具有四取代二芳基醚键的 C-O 二没食子酸酯结构。该方法涉及在黑暗条件下，用 18-冠-6 作为相转移催化剂，使溴代-醌单缩酮与具有六羟基二苯甲酰基部分的酚发生氧杂迈克尔加成/消除反应，然后进行还原芳构化。还讨论了由构建的醚部分引起的构象异构体的存在。
