1. Total Synthesis of (—)-Acetylaranotin Hideto Fujiwara, Taichi Kurogi, Shun Okaya, Kentaro Okano, and Hidetoshi Tokuyama* Angew. Chem. Int. Ed. 2012, 51, 1 – 5 Speaker: 王湘閔

2. Introduction 1.Epidithiodiketopiperazine (ETP) core 2.Dihydrooxepine

3.  Isolation:  Isolation: (-)-Acetylaranotin (1) was first isolated over 40 years ago and that the first synthesis of the biosynthetically related compound gliotoxin was reported in 1976.   Biological activities: Inhibitory activity against viral RNA polymerase, potent antituberculous activity, antiproliferative activity against DU145 human prostate cancer cell line. Isolation and Biological activities

4. Past Work 1. General methods for dihydrooxepine formation 2. First total synthesis of ( — )-Acetylaranotin The first tactical consideration: identification of conditions for oxidation of the diketopiperazine C-H bonds in the presence of the dihydrooxepine moiety. The preparation of 9 raises the second key tactical consideration: construction of the dihydrooxepine moiety.

5. Retrosynthetic Analysis

6. Synthesis of substrate 20 for Baeyer-Villiger oxidation Synthesis of substrate 20 for Baeyer-Villiger oxidation vinylogous Rubottom oxidation

7. Synthesis of dihydrooxepine 23

8. Dimerization of monomer

9. Preparation of monomers possessing the stereochemistry of natural product Low yield

10. Total Synthesis of (—)-Acetylaranotin (1)

11.  Total synthesis of ( — )-acetylaranotin (1) was accomplished in 22 steps (0.06% overall yield) from commercially available L-Cbz-tyrosine.  The approach features the efficient formation of the proline-fused dihydrooxepine ring through unusual vinylogous Rubottom oxidation, and successful dimerization of the monomer unit, which possesses an unnatural stereochemistry. Conclusion  Total synthesis of ( — )-acetylaranotin (1) was accomplished in 22 steps (0.06% overall yield) from commercially available L-Cbz-tyrosine.  The approach features the efficient formation of the proline-fused dihydrooxepine ring through unusual vinylogous Rubottom oxidation, and successful dimerization of the monomer unit, which possesses an unnatural stereochemistry.

12. Summary