Efficient Synthetic Routes to (±)‐Hippolachnin A, (±)‐Gracilioethers E and F and the Alleged Structure of (±)‐Gracilioether I

• Published in: Chemistry : a European journal Vol. 23; no. 9; pp. 2026 - 2030
• Main Authors: Xu, Ze‐Jun, Wu, Yikang
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 10.02.2017
• Subjects: Chemistry; Chemistry, Multidisciplinary; condensation; cycloaddition; Cycloaddition Reaction; cyclocarbonylation; Ethers, Cyclic - chemical synthesis; Ethers, Cyclic - chemistry; Heterocyclic Compounds, 3-Ring - chemical synthesis; Heterocyclic Compounds, 3-Ring - chemistry; lactones; Molecular Conformation; oxidation; Oxidation-Reduction; Physical Sciences; Polyketides - chemical synthesis; Polyketides - chemistry; Science & Technology; Stereoisomerism; Temperature; lactones; METABOLITES; cycloaddition; SPONGE; cyclocarbonylation; ESTERS; condensation; oxidation; C-H OXIDATION; SAMARIUM(II) IODIDE; PLAKORTIS
• ISSN: 0947-6539; 1521-3765; 1521-3765
• DOI: 10.1002/chem.201605776

Two monocyclic members in the gracilioether family were synthesized in only three steps. The monocyclic products were further elaborated into advanced precursors to hippolachnin A and gracilioether E, respectively. Gracilioether F and the alleged structure for gracilioether I were also synthesized using a late‐stage C(sp3)–H thermo‐oxidation. Members of the family: The carbonyl group at the C‐1 made the C‐2 oxidation more difficult than otherwise. However, eventually the Pb(OAc)4/I2/80 °C conditions worked well where other conditions failed. The last step oxidation along with several other novel steps created a quick route to several members in the gracilioether family, including the alleged structure for gracilioether I.