Hernández-Torres Gloria, Urbano Antonio, Carreño M Carmen, Colobert Françoise
Departamento de Química Orgánica (C-I), Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain.
Org Lett. 2009 Nov 5;11(21):4930-3. doi: 10.1021/ol9020783.
(2R,4'RS,8'RS)-alpha-tocopherol (1) was prepared using, as the two key steps, a novel diastereoselective TiCl(4)-promoted (S)-sulfoxide-directed allylation of ketal 2 with allyl trimethyl silane 3 to efficiently generate the challenging (2R) stereocenter of the chroman moiety and a cross-metathesis reaction with olefin 4 to efficiently join the lipophilic alkyl chain present in the final target.
（2R，4'RS，8'RS）-α-生育酚（1）的制备采用了两个关键步骤：一是新颖的非对映选择性TiCl₄促进的（S）-亚砜导向的缩酮2与烯丙基三甲基硅烷3的烯丙基化反应，以高效生成色满部分具有挑战性的（2R）立体中心；二是与烯烃4进行交叉复分解反应，以有效地连接最终目标中存在的亲脂性烷基链。
