18O assisted analysis of a γ,δ-epoxyketone cyclization: synthesis of the C16-C28 fragment of ammocidin D.
The C16-C28 fragment common to the cytotoxic macrolide ammocidin D has been prepared by a stereospecific 5-exo closure of a γ,δ-epoxyketone followed by a rearrangement to a pyran acetal. The reaction pathway was traced by (18)O labeling of the keto carbonyl and observation of (18)O induced (13)C shifts in the pyran acetal product. NMR data of the synthetic C16-C28 fragment compared favorably to the natural product providing support of the assigned stereochemistry.
Department of Chemistry, Vanderbilt University, Vanderbilt Institute of Chemical Biology, Nashville, Tennessee 37235, USA.
Stephen T
ST
Chau
Yoichi
Y
Hayakawa
Gary A
GA
Sulikowski
D003500:Cyclization; D018942:Macrolides / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D010103:Oxygen Isotopes; D011714:Pyrans / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
D018942:Macrolides; D010103:Oxygen Isotopes; D011714:Pyrans; C544240:ammocidin D
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