Synthesis of the C1 – C16 fragment of bryostatin for incorporation into 20,20-fluorinated analogues
作者:Paul R. Mears、Eric J. Thomas
DOI:10.1016/j.tet.2020.131743
日期:2021.1
The stereoselective synthesis of a carboxylic acid ester corresponding to the C1–C16 fragment of bryostatin, with 4-methoxybenzyl (PMB) protection for the 7-hydroxyl group, is reported. The key steps included a Horner-Wadsworth-Emmons reaction between (5R)-3-[(E)-2-tri-isopropylsilyloxyethylidene]-6-(4-methoxybenzyloxy)-5-triethylsilyloxyhexanal and dimethyl (4S,6R,8S)-10-hydroxy-6,8-di-O-isopropy
据报道,立体选择性合成了与抑霉菌素C1-C16片段相对应的羧酸酯,其中4-羟基甲氧基苄基(PMB)保护7-羟基。关键步骤包括(5 R)-3-[(E)-2-三异丙基甲硅烷氧基乙叉基] -6-(4-甲氧基苄氧基)-5-三乙基甲硅烷氧基己醛与二甲基(4 S,6 R之间的Horner-Wadsworth-Emmons反应,8 S)-10-羟基-6,8-二-O-异亚丙基-4-(4-甲氧基苄氧基)-3,3-二甲基-2-氧杂癸-1-基膦酸酯,得到相应的(E)-烯烃,然后选择性裂解三乙基甲硅烷基醚并环化,得到所需的2,6-顺式-二取代的4-[(Z)-三异丙基甲硅烷氧基乙氧基]四氢吡喃。伯醇的氧化得到相应的羧酸,将其转化为所需的烯丙基酯。