A novel one-flask cyclopentannulation involving a dilithiomethane equivalent as a β-connector of two enones. A highly efficient total synthesis of (±)-hirsutene
作者:Theodore Cohen、Kevin McNamara、Michael A. Kuzemko、Keith Ramig、John J. Landi、Yong Dong
DOI:10.1016/s0040-4020(01)88017-0
日期:1993.9
tris(phenylthio)methyllithium. The latter behaves as a dilithiomethane equivalent when its central carbon atom adds in conjugate fashion to one enone, becomes nucleophilic again when one of its phenylthio groups is exchanged for lithium in the presence of sec-butyllithium, and then undergoes conjugate addition to a second enone to provide a dienolate dianion. The latter can be oxidized to a 1,4-diketone incorporating
可以在一个烧瓶中由两种不同的烯酮和三(苯硫基)甲基锂构成五元和六元环。当其中心碳原子以共轭方式加成一个烯酮时,后者表现为二硫代甲烷当量,当其仲苯基存在时,当其一个苯基硫代基团交换成锂时,后者又变为亲核性-丁基锂,然后进行共轭加成至第二烯酮以提供二烯酸二阴离子。后者可被氧化成带有环戊烷环的1,4-二酮,或被诱导进行羟醛反应以产生六元环。在某些情况下,氧化过程中会发生有趣的立体化学平衡,从而导致两种可能的非对映异构体之一,并且整个过程导致(±)-hirsutene 13的高效立体定向合成。