Sulfinamide-Based Approach for Synthesis of the Pentacyclic Core of Nakadomarin A

The synthesis of the pentacyclic core of alkaloid nakadomarin A is described. Key reactions in the synthesis include the elaboration of a Michael addition product obtained in the addition of a chiral sulfinyl imidate to an unsaturated ester prepared from 3-furyl aldehyde; diastereoselective allylation of a β-keto ester; and intramolecular cyclization of furan onto an iminium ion.