Breder A Chinigo GM Waltman AW Carreira EM 2011 Massadine is a hexacyclic marine natural product, which belongs to the family of pyrrole-imidazole alkaloids. Herein, we describe a unified approach to the C,D-ring subunit of this sponge metabolite based on the exploitation of a norbornene scaffold for the stereocontrolled construction of massadine's carbon skeleton. Highlights of the sequence presented include the application of a stereospecific norbornyl rearrangement for facile introduction of an oxygen at the C7-position within the norbornene nucleus, a highly regioselective and end group differentiating ozonolytic scission of a C-C double bond, and an oxidative decarboxylation reaction for the installation of the hindered secondary C2-alcohol function. Furthermore, the iterative assembly of the two guanidine entities as well as the implementation of the spirocyclic junction between the C- and the D-rings are described. Collectively, these key transformations permit an entry to an appropriately functionalized carbon framework, which will serve as a starting point for our efforts toward the completion of the synthesis of massadine. https://sonar.ch/global/documents/167893 eng info:eu-repo/semantics/altIdentifier/doi/10.1002/chem.201101862 info:eu-repo/semantics/altIdentifier/pmid/21932242 Chemistry (Weinheim an der Bergstrasse, Germany). - 2011 Alkaloids Biological Products Oxidation-Reduction Polycyclic Compounds Pyrroles Stereoisomerism Towards the synthesis of massadine: a unified strategy for the stereoselective synthesis of the carbocyclic C,D-ring subunit. http://purl.org/coar/resource_type/c_6501