Enantioselective Synthesis of (−)-Acetylapoaranotin

The first enantioselective total synthesis of the epipolythiodiketopiperazine (ETP) natural product (−)-acetylapoaranotin (3) is reported. The concise synthesis was enabled by an eight-step synthesis of a key cyclohexadienol-containing amino ester building block. The absolute stereochemistry of both amino ester building blocks used in the synthesis is set through catalytic asymmetric (1,3)-dipolar cycloaddition reactions. The formal syntheses of (−)-emethallicin E and (−)-haemotocin are also achieved through the preparation of a symmetric cyclohexadienol-containing diketopiperazine