Expeditious Asymmetric Synthesis of a Stereoheptad Corresponding to the C(19)-C(27)-Ansa Chain of Rifamycins: Formal Total Synthesis of Rifamycin S
作者:M?ris Turks、Xiaogen Huang、Pierre Vogel
DOI:10.1002/chem.200400825
日期:2005.1.7
In the presence of sulfur dioxide and an acid promoter, (-)-(1E,3Z)-2-methyl-1-((1S)-1-phenylethoxy)penta-1,3-dien-3-yl isobutyrate reacts with (Z)-3-(trimethylsilyloxy)pent-2-ene giving a silyl sulfinate intermediate that undergoes, in the presence of palladium catalyst, a desilylation and retro-ene elimination of SO(2) with formation of (-)-(1Z,2S,3R,4S)-1-ethylidene-2,4-dimethyl-5-oxo-3-((1S)-1
在二氧化硫和酸促进剂的存在下,(-)-(1E,3Z)-2-甲基-1-(((1S)-1-苯基乙氧基)戊-1,3-二烯-3-基异丁酸酯)与(Z)-3-(三甲基甲硅烷氧基)戊-2-烯生成甲硅烷基亚磺酸盐中间体,该中间体在钯催化剂存在下经历SO(2)的脱甲硅烷基化和逆烯消除,形成(-)-(1Z主要产物,, 2S,3R,4S)-1-亚乙基-2,4-二甲基-5-氧代-3-((1S)-1-苯基乙氧基)-庚基异丁酸酯。该乙基酮与(2S)-2-甲基-3-[[叔丁基二甲基甲硅烷基)氧基]丙醛发生交叉醇醛反应,得到醇醛,该醇醛被还原成对应于C(19)-C(27)-高非对映选择性和对映体过量的利福霉素的部分。