Department of Organic Synthesis & Process Chemistry, Indian Institute of Chemical Technology, Hyderabad 500007, India.
Org Biomol Chem. 2019 May 8;17(18):4572-4592. doi: 10.1039/c9ob00623k.
The stereoselective synthesis of solandelactone F, constanolactone A and an advanced intermediate towards solandelactone E, from a common synthetic intermediate, is disclosed. The propargylic sulfide stereocenter is created stereoselectively via carbon-carbon bond formation in the reaction of α-chloro sulfides with alkynylzinc reagents via 1,2-asymmetric induction by a β-siloxy group. The characteristic 1,4-diol motif of the natural products is introduced by a [2,3] sigmatropic rearrangement of an allylic sulfoxide or by the Mislow-Evans-Braverman rearrangement of a propargylic sulfoxide followed by stereoselective reduction of the ensuing α,β-unsaturated ketone. Unlike earlier reports, the C11/C9 carbinol center is created with excellent stereocontrol and derivatives of natural products differing at C14/C12 can be readily obtained. Catalytic asymmetric protocols and substrate-controlled asymmetric induction are utilized for the efficient introduction of the stereogenic centers.
本文披露了从一个共同的合成中间体立体选择性地合成索兰内酯 F、康纳内酯 A 和索兰内酯 E 的一个高级中间体。通过β-硅氧基的 1,2-不对称诱导，α-氯代硫醚与炔基锌试剂的碳-碳键形成反应中立体选择性地生成了丙炔基硫化物的立体中心。天然产物的特征 1,4-二醇基序是通过烯丙基砜的[2,3]西格玛重排或丙炔基砜的 Mislow-Evans-Braverman 重排引入的，然后对随后的α,β-不饱和酮进行立体选择性还原。与早期报道不同的是，C11/C9 碳原子中心的立体选择性控制非常好，可以很容易地获得 C14/C12 处不同的天然产物衍生物。催化不对称方案和底物控制的不对称诱导被用于有效引入手性中心。
