Synthesis of the GHIJKL Fragment of Gymnocin-B

Abstract

The GHIJKL fragment of gymnocin-B was synthesized using the oxiranyl anion strategy. The first highlight of the synthesis is the bromoketone cyclization reaction on the oxepane ring to construct the fused bisoxepane GH ring. The second key step is the introduction of the trans-4-hydroxy-3-methyloxepane J ring via addition of trimethylaluminum to a conjugated oxonium moiety, followed by diastereoselective epoxidation and regioselective reduction.

Six-membered ring systems: with O and/or S atoms

“…Reductive Heck cyclization for the construction of the DEF-benzoxocin ring system of nogalamycin and menogaril (19JOC173), construction of ABCDEF-ring system in the total synthesis of nogalamycin (19JOC760), synthesis of difluorinated tetrahydropyran moieties for the synthesis of various 20,20-difluorinated C17eC27 fragments of natural bryostatin (19OBC1487), synthesis of tetrahydropyran-containing GHIJKL fragment of gymnocin-B (19OL6864), and synthesis of tetrahydropyran unit in the macrolactone core of neopeltolide (19TL432) have all been surveyed.…”