Stereoselective Synthesis of Benzylated Prodelphinidins and Their Diastereomers with Use of the Mitsunobu Reaction in the Preparation of Their Gallocatechin Precursors
作者:Karsten Krohn、Ishtiaq Ahmed、Markus John、Matthias C. Letzel、Dietmar Kuck
DOI:10.1002/ejoc.201000053
日期:2010.5
coupled with the commercially unavailable pentabenzylated (-)-gallocatechin 10, prepared in a one-step Mitsunobu-type cyclization of the triol 8 The highly stereoselective synthesis of benzylated prodelphinidins - catechin-(4 alpha -> 8)-gallocatechin (13), gallocatechin-(4 alpha -> 8)-gallocatechin (14), and gallocatechin-(4 alpha -> 8)-catechin (15) - is reported for the first time. The ESI(+)-CID mass
四苄基化儿茶素 9 是通过将市售的纯 (+)-儿茶素 (3) 苄基化并与市售的五苄基化 (-)-没食子儿茶素 10 偶联制备的,通过三醇 8 的一步 Mitsunobu 型环化制备。苄基化前飞燕草素的高度立体选择性合成 - 儿茶素-(4 α -> 8)-没食子儿茶素 (13)、没食子儿茶素-(4 α -> 8)-没食子儿茶素 (14) 和没食子儿茶素-(4 α -> 8)-儿茶素 ( 15) - 首次报道。发现偶联产物的 ESI(+)-CID 质谱具有区域选择性逆狄尔斯-阿尔德 (RDA) 反应和来自 Na+ 加合离子的 C7H7 自由基对 (182 u) 的异常连续损失