Unprecedented Water Addition to the α,β‐Unsaturated Enone Bond, Mediated by the Combination of Carbonate and Platinum(II)

Abstract

The cytostatic compounds cis-[Pt(A9pyp)(dmso)Cl(2)] (1) and [Pt(A9pyp)(dmso)(cbdca)] (2) (A9pyp=(E)-[1-(9-anthryl)-3-(2-pyridyl)-2-propenone) as carrier ligand; cbdca=cyclobutane dicarboxylate) have been found to add water across the enone C==C bond of the ligand A9pyp. The water addition occurs in the presence of carbonate buffer, and has been followed in detail using NMR and ESI-MS spectroscopy. The spectroscopic data clearly indicate that the platinum(II) ion, the carbonate species, and the proximity of the enone C==C bond to the metal ion, are all required for this unusual hydration. A difference in kinetics is observed between chloride and cbdca, showing that the Pt-ligand dissociation plays an important role in the hydration kinetics.

Biomimetic Syntheses of (−)-Gochnatiolides A–C and (−)-Ainsliadimer B

“…Clearly, a direct chemo- and regioselective water addition to the exomethylene–cyclopentenone moiety of 2 in the presence of two α-methylene-γ-butyrolactones would be ideal. However, the direct enone hydration for the synthesis of a β-hydroxy ketone has rarely been reported and proved to be challenging. As shown in Scheme , we initially screened both basic and phosphine-catalyzed conditions for direct hydration as well as the literature-reported stepwise procedures for the installation of a β-hydroxy ketone, but unfortunately, all of these attempts failed.…”