An Exceptionally Short and Simple Enantioselective Total Synthesis of Pentacyclic Triterpenes of the β-Amyrin Family
作者:Alan X. Huang、Zhaoming Xiong、E. J. Corey
DOI:10.1021/ja992411p
日期:1999.11.1
A new and very direct enantioselective total synthesis of members of the β-amyrin family of pentacyclic triterpenes has been developed starting with acylsilane 5, 2-propenyllithium, and cyclohexenylmethyl bromide 6, which were assembled to form tetraene 7. Cationic cyclization of 7 and silylation afforded 8, which after vinyl triflate formation was cyclized via a Cu(I) intermediate (Scheme 2) to form
以酰基硅烷 5、2-丙烯基锂和环己烯基甲基溴 6 为起始,开发了一种新的非常直接的对映选择性全合成五环三萜类 β-香树脂醇家族成员,它们组装形成四烯 7。 7 的阳离子环化和甲硅烷基化得到 8,在三氟甲磺酸乙烯酯形成后通过 Cu(I) 中间体(方案 2)环化形成 aegiceradienol 10 的 TBS 醚,这是一种多功能中间体,很容易转化为天然 β-香树脂醇,如 β-香树脂醇 (1)和齐墩果酸 (2)。也使用分子内Stille反应封闭环D,由8的C(14)-非对映异构体合成了癸二烯醇的C(14)-非对映异构体(13)(方案4)。