SYNTHESIS OF 3α-HYDROXY-5β,10β-EPOXYCHILIOLIDE, AN ISOLABDANE DERIVATIVE FROM CHILIOTRICHIUM ROSMARINIFOLIUM

Article abstract of DOI:10.1016/S0040-4020(01)85095-X

Starting with 6-methoxytetralone the unusual diterpene 3α-hydroxy-5β,10β-epoxychiliolide(15a) has been synthesized via methyl<1α,2α>-1,2,3,4,5,6,7,8-octahydro-6-oxo-1-(2-propenyl)-2,5,5-trimethyl-1-naphthoate (9) which by boranate reduction gave the desired α-hydroxy derivative.Oxidative degradation of the propenyl side chain afforded the aldehyde 11a which could be transformed to the racemic furan diterpene 15a by reaction with 3-lithiumfuran followed by lactonization and epoxidation.Similar the epimeric compound 15b, 15c and 15d were synthesized which allowed a final proof of the proposed relative stereochemistry of the six chiral centers of the natural compound.