Synthesis of the Proposed Structure of Celacarfurine and Analogues Using Sequential Cascade Ring Expansion Reactions

The first synthesis of the proposed structure of spermidine derived macrocyclic alkaloid celacarfurine is described. A versatile synthetic strategy has been developed based on sequential cascade ring expansion reactions, with high dilution conditions not needed for any of the steps. The same general strategy was also used to generate a series of macrocyclic analogues. The physical properties and spectroscopic data obtained for our synthetic product do not match those reported for the isolated alkaloid.