Details

Autor(en) / Beteiligte

• Clark, J. Stephen
• Berger, Raphaëlle
• Hayes, Stewart T
• Senn, Hans Martin
• Farrugia, Louis J
• Thomas, Lynne H
• Morrison, Angus J
• Gobbi, Luca

Titel

Total Syntheses of Multiple Cladiellin Natural Products by Use of a Completely General Strategy

Ist Teil von

• Journal of organic chemistry, 2013-01, Vol.78 (2), p.673-696

Ort / Verlag

United States: American Chemical Society

Erscheinungsjahr

2013

Quelle

MEDLINE

Beschreibungen/Notizen

• The enantioselective total syntheses of 10 cladiellin natural products have been completed, starting from the known allylic alcohol (+)-14, which can be prepared in large quantities. The bridged tricyclic core of the cladiellins has been constructed via three ring-forming reactions: (i) an intramolecular reductive cyclization between an aldehyde and an unsaturated ester, mediated by samarium(II) iodide, to form a tetrahydropyranol; (ii) reaction of a metal carbenoid, generated from a diazo ketone, with an ether to produce an ylide-like intermediate that rearranges to produce E- or Z-oxabicyclo[6.2.1]-5-undecen-9-one; and (iii) a Diels–Alder cycloaddition reaction to construct the third ring found in the core structure of the cladiellins. The key ring-forming reaction, in which a diazo ketone is converted into a bridged bicyclic ether, can be tuned to give either of the isomeric oxabicyclo[6.2.1]-5-undecen-9-ones as the major product by switching from a copper to a rhodium catalyst and selecting the appropriate reaction conditions. The tricyclic products obtained from the three-step sequence involving the Diels–Alder cycloaddition reaction can be employed as advanced intermediates to prepare a wide range of cladiellin natural products.