First total synthesis of ent-asperparaline C and assignment of the absolute configuration of asperparaline C

The first asymmetric total synthesis of a member of the asperparaline family was accomplished and the unknown absolute configuration of asperparaline C has been determined to be all-(S). The key steps of the synthesis are an oxidative radical cyclization, a selective reduction of one of the tertiary amides, a singlet oxygen Diels-Alder reaction and a reductive spirocyclization.