Gurjar Mukund K, Karumudi Bhargava, Ramana C V
National Chemical Laboratory, Dr. Homi Bhabha Road, Pune - 411 008, India.
J Org Chem. 2005 Nov 11;70(23):9658-61. doi: 10.1021/jo0516234.
[Reaction: see text]. The Zn-mediated Barbier reaction of the biarylaldehyde 8 with crotyl bromide followed by hydroboration and oxidation provided the gamma-butyrolactones 4 and 5. The stereoselective installation of methyl group at C-3 by using LiHMDS and MeI completed the synthesis of racemic eupomatilone-6 (2) and its diastereomer 3. The spectroscopic data of 2 was in full agreement with reported spectra of natural product, thus confirming the revised relative configuration of eupomatilone-6. Similarly, an optically active (3R,4R,5S)-isomer of eupomatilone-6 (23) was prepared in which the aldol reaction with thiazolidinethione as a chiral auxiliary was employed as a key step. On the basis of the spectroscopic data and optical rotation values of 23, the absolute configuration of eupomatilone-6 was proposed.
[反应：见正文]。联芳醛8与巴豆基溴在锌介导下发生巴比耶反应，随后进行硼氢化和氧化反应，得到了γ-丁内酯4和5。使用二异丙基氨基锂（LiHMDS）和碘甲烷在C-3位立体选择性地引入甲基，完成了外消旋优巴替隆-6（2）及其非对映异构体3的合成。2的光谱数据与天然产物报道的光谱完全一致，从而确定了优巴替隆-6的修正相对构型。同样，制备了优巴替隆-6的光学活性（3R,4R,5S）-异构体（23），其中以噻唑烷硫酮作为手性助剂的羟醛反应作为关键步骤。基于23的光谱数据和旋光值，提出了优巴替隆-6的绝对构型。
