Two efficient four-step routes to marine toxin tanikolide

We have presented two facile four-step syntheses of (±)-tanikolide from ethyl 2-oxocyclopentanecarboxylate. The overall chemical yields of the two sequences reached as high as 76 and 85%, respectively. The first strategy involved alkylation, Baeyer-Villiger reaction, saponification, and reduction/lactonization. The second approach for synthesizing tanikolide took advantage of the same intermediate, the alkylated ketoester 2, which was converted to the target molecule in such three steps as deethoxycarbonylation, hydroxymethylation, and Baeyer-Villiger reaction. Our strategies are advantageous because of their high yields and suitability for the preparation of 1 in multigram or larger quantities.