Total Synthesis of Marine Natural Product Sunshinamide via Macrolactonization

A new approach for the synthesis of marine natural product Sunshinamide has been developed, featuring macrolactonization as a key step. The important synthetic strategy is to first construct the unique 8-membered cyclic dithiazocane in the earlier stage and finally carry out macrolactonization according to Shiina's method. Compared with the reported macrolactamization of a linear precursor, the macrolactonization bearing the cyclic dithiazocane scaffold resulted in a lower macrocyclization yield, implying that the cyclic dithiazocane might not offer a more favorable conformational constraint for macrocyclization.