113453-35-3Relevant academic research and scientific papers
Total synthesis of the polyether antibiotic X-206
Evans,Bender,Morris
, p. 2506 - 2526 (2007/10/12)
A convergent asymmetric synthesis of the polyether antibiotic X-206 has been achieved through the synthesis and coupling of the C1-C16- and C17-C37 synthons 16 and 17, respectively. All absolute stereochemical relationships within the molecule were controlled by application of recent methodological advances in asymmetric synthesis. In the synthesis of subunit 16, both the alkylation and aldol reactions of chiral imide-derived enolates were utilized to establish the five stereogenic centers at C2-C4 and C9-C10, while the stereochemistry at C14 was indirectly controlled by the Sharpless asymmetric epoxidation. The C7 and C11 stereocenters, which are situated at the two assemblage points for 16, were established through internal asymmetric induction. The synthesis of the more complex C17-C37 subunit 17 followed a similar strategy for absolute stereocontrol. Chiral enolate methodology was employed to define the stereogenic centers at C18, C22, and C23 while asymmetric epoxidation was used to create the oxygen-bearing centers at C30-C31 and C34-C35. The remaining three stereogenic centers at C20, C26, and C28 were controlled by internal asymmetric induction. The successful construction of this synthon relied upon the development of an efficient assemblage reaction in which three fragments comprising the entire carbon framework of 17 were united in a single operation. The final coupling of the two halves was achieved by a nonstereoselective aldol reaction. In supporting studies, the selective manipulation and degradation of the natural product were also investigated.
