Based on this analysis, we started to synthesize all possible remaining 16 diastereomers of Corramycin to compare the respective NMR data with those of the isolated natural product. A solid-phase peptide synthesis (SPPS) approach with a traditional Fmoc-strategy and adequate protecting groups on the different hydroxyl groups was used to synthesize Corramycin starting from L-serine. The non-proteinogenic protected amino acids β-hydroxy-valine (10), 2,3-dihydroxybutyric acid (7), N-methyl-βhydroxy-histdine (8), and 5-amino-2,3-dihydroxy-4methoxyvaleric acid (9) were synthesized from commercially available building blocks as shown in the retrosynthetic scheme (Figure ). Building block 10 was easily accessible by using a described strategy starting from D-Serine (Supplementary Figure S 28) as well as building block 7, which was obtained via saponification of commercially available ester 11 (Supplementary Figure S 31). More steps were necessary for the synthesis of building block 9 (Supplementary Figure S 29), starting from a protected and commercial derivative of L-ribose (14). Transformation of the free alcohol as leaving group, followed by azido formation, lactone opening with a protected phenylalanine derivative (15) and several protection-, oxidation-and reduction-steps allowed to obtain building block 9 in an overall acceptable yield. For the last building block 8, we achieved to create the two stereocenters by enantioselective aldolisation using a titanium enolate derived from a chiral iminoglycinate (Supplementary Figure S 30). Using α-pinene as a chiral auxiliary, an oxidation step followed by imine formation with protected glycine (12) delivered the starting compound for the aldolization step, followed by a few protection/deprotection steps. The synthesis route was finalized via a traditional Fmoc-SPPS in standard conditions (HATU, DIEA, DMF, room temperature) starting from Fmoc-L-TBDMSO-serine (Supplementary Figure S 32). Comparison of the NMR data of all 16 diastereomers with the NMR data of the isolated Corramycin confirmed the configurational correctness of the analysis and the in silico prediction. Furthermore, we elucidated the configuration of the missing stereocenters, providing the absolute configuration of Corramycin (Figure ). The complete total synthesis is described in detail in the SI. Labelling with a star: predicted stereocenters after the in silico analysis of the BGC.