The convergent synthesis of macrolide soraphen A1α is described starting from glucose (western part) and mannose (eastern part). Mannose was converted into a 2-deoxyribohexapyranoside that could be methylated and reduced stereoselectively. Chain elongation at C-6 was carried out by stereoselective addition of a magnesium acetylide. The two fragments (western and eastern) were assembled by a Julia olefination followed by macrolactonization. The introduction of the methyl group at C-2 of norsoraphen occurred stereoselectively for thermodynamic reasons.
描述了大环抗生素索拉芬A1α的收敛合成,起始于
葡萄糖(西部部分)和
甘露糖(东部部分)。
甘露糖被转化为
2-脱氧核糖六聚糖,可以进行甲基化和立体选择性还原。通过立体选择性添加
镁乙炔在C-6进行链延伸。这两个片段(西部和东部)通过朱莉醇化反应结合,随后进行大环内酯化。在反应中,由于热力学原因,甲基团在诺索拉芬的C-2位引入是立体选择性的。