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。
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.
Together with eleven known compounds (1-11), seven new tannins, 3-desgalloylterchebin (12), macaranins A, B and C, and macarinins A, B and C, have been isolated from the leaves of Macaranga sinensis (BAILL.) MUELL.-ARG. (Euphorbiaceae). Macaranins A (14), B (13) and C (17) have been determined on the basis of chemical and spectroscopic evidence to be hydrolyzable tannins possessing a novel acyl group (macaranoly group) at the 3, 6-positions of the 1C4 (or skew boat) β-D-glucopyranose ring, while macarinins A (18), B (15) and (16) were characterized as those having a tergalloyl group at the same positions.