Regulated-Stereoselective Construction of Thirteen Stereogenic Centers Necessary for the Frame of (+)-Discodermolide, Based on Iterative Lewis Acid-Promoted Aldol Reactions
作者:Syun-ichi Kiyooka、Kazi Abdus Shahid、Fumitaka Goto、Momotoshi Okazaki、Yoshihiro Shuto
DOI:10.1021/jo034901c
日期:2003.10.1
and diastereoselective (BF(3).OEt(2) and TiCl(4)) aldol reactions with the silylketene acetal, coupled with diastereoselective radical debrominations (Bu(3)SnH, Et(3)B, with or without MgBr(2)), were used iteratively. This aldol reaction strategy for the construction of the polypropionate frame dramatically shortened the steps needed for the construction of the final segments.
包含(+)-discodermolide框架所需的13个立体异构中心的C(1)-C(13)和C(15)-C(21)片段是由一种常见的外消旋体以良好至优异的对映选择性和非对映选择性合成的醛,衍生自2-甲基-1,3-丙二醇。外消旋醛与2-溴丙酸乙酯衍生的甲硅烷基乙烯酮缩醛的对映体选择性醛醇缩合反应,在手性草氮杂硼烷酮存在下,用N-甲苯磺酰基-(R)-和-(S)-缬氨酸和BH(3)原位制备THF,在动力学控制下进行,得到具有高度对映选择性的立体三单元组。对映选择性(手性硼烷)和非对映选择性(BF(3).OEt(2)和TiCl(4))与硅烷基乙烯酮缩醛的醛醇缩合反应,与非对映选择性自由基脱溴反应(Bu(3)SnH,Et(3)B,或没有MgBr(2)),被迭代使用。这种用于聚丙烯酸酯框架构建的羟醛反应策略大大缩短了构建最终链段所需的步骤。