Syntheses of (5E)-PGE2 and New 6-Functionalized Derivatives by the Use of Palladium-Catalyzed Decarboxylative Allylic Alkylation

Article abstract of DOI:10.1016/S0040-4020(01)82115-3

(5E)-Prostaglandin E₂ (7) was synthesized form (R)-4-t-butyldimethylsilyloxy-2-cyclopentenone (1) by in situ 2-alkenyloxycarbonylation of the organocopper conjugate-addition adduct (3) followed by intramolecular palladium-catalyzed decarboxylative allylic alkylation.The (5E)-prostaglandin E₂ skeleton was also obtained from the β-keto allylic ester (11) by a similar decarboxylative allylic alkylation.The decarboxylative allylic alkylation of another type of the three-component coupling product (12) gave new 6-methyleneprostaglandin E₁ skeleton (15a), which was converted into new 6-methylprostaglandin I methyl ester (20) via 6-methyleneprostaglandin F_1α derivative (16) by two different ways.The stereochemistry of this intramolecular decarboxylative allylic alkylation was discussed in the reaction of 2-<(E)- or (Z)-2-butenyloxycarbonyl>cyclopentanone systems.