Oxidative spirocyclisation routes towards the sawaranospirolides. Synthesis of ent-sawaranospirolides C and D.
Two routes are described for the synthesis of the sawaranospirolides, stereoisomeric spirolactone ascorbigenins isolated from Chamaecyparis pisifera. Trapping of the keto enal formed by oxidation of a functionalised 2-(4-hydroxybutyl)furan affords a potential butenolide spiroacetal precursor to sawaranospirolides A and C. Alternatively, epoxidation of protected 3-(dihydropyran-2-yl)-3-arylpropanoic acids results in spirolactonisation to generate ent-sawaranospirolide C; a related acid-mediated spirocyclisation gave access to ent-sawaranospirolide D.
Robertson
Jeremy
J
Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford, UKOX1 3TA. jeremy.robertson@chem.ox.ac.uk
Chovatia
Praful T
PT
Fowler
Thomas G
TG
Withey
Jonathan M
JM
Woollaston
Daniel J
DJ
D029780:Chamaecyparis / Q000737:chemistry*; D003500:Cyclization; D010084:Oxidation-Reduction; D013141:Spiro Compounds / Q000138:chemical synthesis*; D013237:Stereoisomerism
D013141:Spiro Compounds; C429215:spirolide A; C429216:spirolide C; C467769:spirolide D