An efficient synthesis of diquinane-based bis-γ-lactones

An efficient stereoselective synthesis of both the diastereomers of diquinane-based conformationally constrained symmetric bis-γ-lactones starting from tricyclic derivative 9 is reported. The key step involves the intramolecular ring opening of an epoxide by the in situ formed hydrate of a diketone leading to the tetracyclic hemiacetal 10, which directly leads to the exo-hydroxy bis-γ-lactone derivatives 2 and 4 under basic hydrogen peroxide cleavage conditions. Conversion to the endo-hydroxy bis-γ-lactone derivatives 1 and 3 was accomplished through lithium hydroxide mediated SN2 displacements in dimesylate 7, or more expeditiously, via trimesylate 21 through alkaline H2O2 mediated cleavage.

Graphical abstractAn efficient stereoselective synthesis of both the diastereomers of diquinane-based conformationally constrained symmetric bis-γ-lactones starting from tricyclic derivative 9 is reported.Figure optionsDownload full-size imageDownload as PowerPoint slide