Total Synthesis of Soraphen A1α

Abstract

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.