Inside Back Cover: Diastereoselective Synthesis of Cyclopentanoids: Applications to the Construction of the ABCD Tetracyclic Core of Retigeranic Acid A (Chem. Eur. J. 36/2015).

Tetracyclic carbon skeleton construction: Retigeranic acids are challenging synthetic targets owing to their pentacyclic skeletons that feature an unusual trans ‐ hydrindane ring system, a cyclopentanoid with two quaternary carbon centers at its bridgehead positions, and eight stereogenic centers of which three are quaternary. In their Communication of page 12596 ff., Y. Lan, J. Gong, Z. Yang and co ‐ workers report a concise and efficient construction of the tetracyclic carbon skeleton of retigeranic acid A. Key transformations include a Rh ‐ catalyzed [3+2] cycloaddition of enyol to give the two contiguous quaternary stereocenters at the cyclopentanoid bridgehead positions, and an intramolecular Pauson – Khand reaction to construct the tetracyclic core. [ABSTRACT FROM AUTHOR]