General approach to prostanes B1 by intermolecular pauson-khand reaction: Syntheses of methyl esters of prostaglandin B1 and phytoprostanes 16-B1-PhytoP and 9-L1-PhytoP

Article abstract of DOI:10.1002/ejoc.201201442

A synthetic approach to the methyl esters of Prostaglandin B₁ and Phytoprostanes 16-B₁-PhytoP (PPB₁-I) and 9-L ₁-PhytoP (PPB₁-II) based on the modified Julia olefination of a formylcyclopentenone and an appropriately protected hydroxy sulfone has been developed. The cyclopentenones were efficiently prepared by intermolecular Pauson-Khand reaction of a (silyloxymethyl)alkyne. The sulfone counterpart was prepared by regioselective ring-opening of the appropriate chiral epoxides by 2-mercaptobenzothiazole. The protecting group for the alcohol functionality on the sulfone proved to be crucial. Protection as a tert-butyl ether was the best solution, giving better results than a tert-butyldimethylsilyl ether. A synthetic approach to prostanes B₁ based on Julia olefination of a formylcyclopentenone and an appropriately protected hydroxy sulfone has been developed. Cyclopentenones were prepared by intermolecular Pauson-Khand reaction. Protection of the alcohol functionality of the hydroxy sulfone as a tert-butyl ether proved to be crucial. Copyright