Synthetic Efforts toward the Spiroketal Core of Spirangien A

• Published in: Journal of organic chemistry Vol. 75; no. 15; pp. 5151 - 5163
• Main Authors: Guérinot, Amandine, Lepesqueux, Guillaume, Sablé, Serge, Reymond, Sébastien, Cossy, Janine
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 06.08.2010; Amer Chemical Soc
• Subjects: Acetals - chemical synthesis; Acetals - chemistry; Catalysis; Chemistry; Chemistry, Organic; Exact sciences and technology; Fatty Acids, Unsaturated - chemical synthesis; Fatty Acids, Unsaturated - chemistry; Heterocyclic compounds; Heterocyclic compounds with o, s, se, te hetero atom and condensed derivatives; Iron - chemistry; Magnetic Resonance Spectroscopy; Organic chemistry; Physical Sciences; Preparations and properties; Science & Technology; Spectrometry, Mass, Electrospray Ionization; Stereoisomerism; KETONES; ROUTE; REDUCTION; NATURAL-PRODUCTS; FRAGMENT; ALDOL REACTIONS; ALDEHYDES; (+)-DISCODERMOLIDE; EFFICIENT; SORANGIUM; Catalytic reaction; Spiroketal; Lithium; Transition metal; Iron; Aldehyde; Oxygen heterocycle; Organic carbamate; Ketone; Diastereoselectivity; Spiran; Aldol; Grignard reagent; Olefin; Functionalization; Vinylic compound; Cross reaction; Chemical synthesis; Enolate; Protection; Ethylenic compound
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo100871m

Synthetic studies toward the spiroketal core of spirangien A are described. Two synthetic approaches were developed. Both of them use a diastereoselective aldol addition of a lithium enolate derived from a methyl ketone on an aldehyde. In the first approach, the introduction of the (E)-trisubstituted terminal olefin was achieved by using an iron-catalyzed cross-coupling between an alkyl iodide and a vinyl Grignard reagent and a randomly protected spiroketal was obtained. In the second approach, a highly functionalized spiroketal carbamate, which includes 13 stereogenic centers, was successfully isolated.