Samarium(II)-mediated 4-exo-trig cyclization. A stereocontrolled approach to the core of pestalotiopsin A.
[reaction: see text] Pestalotiopsin A is a structurally unique caryophyllene-type sesquiterpene which has shown immunosuppressive activity and cytotoxicity in preliminary assays. A stereocontrolled approach to the functionalized 2-oxabicyclo[3.2.0]heptane core of pestalotiopsin A is described. The approach includes a samarium(II)-mediated 4-exo-trig cyclization and a trans-lactonization process triggered by the addition of alkylytterbium reagents to a cyclobutanone intermediate.
Johnston
D
D
Department of Chemistry, The Joseph Black Building, University of Glasgow, Glasgow, G12 8QQ Scotland.
Francon
N
N
Edmonds
D J
DJ
Procter
D J
DJ
D003500:Cyclization; D007166:Immunosuppressive Agents / Q000138:chemical synthesis* / Q000737:chemistry; D008968:Molecular Conformation; D012493:Samarium / Q000737:chemistry*; D012717:Sesquiterpenes / Q000138:chemical synthesis* / Q000737:chemistry
D007166:Immunosuppressive Agents; D012717:Sesquiterpenes; C430595:pestalotiopsin A; D012493:Samarium