Enantiospecific Synthesis of (+)-Nemorensic Acid, a Necic Acid Component of the Macropyrrolizidine Alkaloid, Nemorensine
作者:Toshio Honda、Fumihiro Ishikawa
DOI:10.1021/jo990366y
日期:1999.7.1
A concise enantiospecific synthesis of nemorensic acid 3, a necic acid component of the macropyrrolizidine alkaloid nemorensine 2, isolated from Senecio nemorensis L., is described. Reaction of an epsilon-halo-alpha,beta-unsaturated ester (8), readily accessible from a monoterpene (-)-carvone, with samarium iodide gave a fragmentation product (9), where a carbon-carbon bond cleavage reaction occurred
描述了简明的对映体特异性合成的神经烯酸3,其是从Senecio nemorensis L.中分离出来的大吡咯烷核生物碱nemorensine 2的神经酸成分。从单萜(-)-香芹酮容易获得的ε-卤代-α,β-不饱和酯(8)与碘化sa的反应生成了片段化产物(9),在该片段之间发生了碳-碳键裂解反应羰基的γ和δ位置是区域选择性的。9的甲硅烷基的脱保护引起分子内环化,以提供四氢呋喃衍生物(10),其在侧链的化学修饰上得到神经烯酸。