Tetrasubstituted dihydroquinoline portion

The synthesis of the tetrasubstituted dihydroquinoline portion of siomycin Di, which belongs to the thiostrepton family of peptide antibiotics, was achieved in the laboratory of K. Hashimoto. The Jacobsen epoxidation was utilized to introduce the epoxide enantioselectively at the C7-C8 position. The olefin was treated with 5 mol% of Jacobsen s manganese(lll)-salen complex (R =f-Bu) and 4% aqueous NaOCI solution in dichloromethane. To enhance the catalyst turnover, 50 mol% of 4-phenylpyridine-A/-oxide was added to the reaction mixture. The desired epoxide was obtained in 43% yield and with 91% ee. 

Higashibayashi, S., Mori, T., Shinko, K., Hashimoto, K., Nakata, M. Synthetic studies on thiostrepton family of peptide antibiotics synthesis of the tetrasubstituted dihydroquinoline portion of siomycin Di. Heterocycles 2002, 57, 111-122. 

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