Tannins and related compounds. XCVI. Structures of macaranins and macarinins, new hydrolyzable tannins possessing macaranoyl and tergalloyl ester groups, from the leaves of Macaranga sinensis (Baill.) Muell.-Arg.
Tannins and related compounds. XCVI. Structures of macaranins and macarinins, new hydrolyzable tannins possessing macaranoyl and tergalloyl ester groups, from the leaves of Macaranga sinensis (Baill.) Muell.-Arg.
ABSTRACT This study describes the totalsynthesis of macaranin B, a naturally occurring ellagitannin containing 1-O-galloyl and 3,6-O-macaranoyl groups in an axial-rich d-glucose. The key steps of the synthesis include an oxidative coupling reaction of galloyl groups with 1,2,4-orthoacetylglucose moiety and oxa-Michael addition/elimination using an orthoquinone monoketal. This facilitates the construction
摘要 本研究描述了 macarin B 的全合成,这是一种天然存在的鞣花单宁,在富含轴向的 d-葡萄糖中含有 1-O-没食子酰基和 3,6-O-macaranoyl 基团。合成的关键步骤包括没食子酰基与 1,2,4-邻乙酰基葡萄糖部分的氧化偶联反应和使用邻醌单缩酮的 oxa-Michael 添加/消除。这促进了 macaranoyl 基团的构建和 macarin B 的首次全合成。