Highly Stereoselective Total Synthesis of Methynolide, the Aglycon of the 12-Membered Macrolide Antibiotic Methymycin. III. An Efficient Synthesis of Methynolide(Organic,Chemical)

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Methynolide (1), the aglycon of the 12-membered macrolide antibiotic methymycin, was synthesized highly stereoselectively and efficiently from D-glucose via two segments i (3:C-9-C-13) and ii (4: C-1-C-8). Esterifieation of the two segments proceeded smoothly by Yamaguchi's method. When the resulting ester (10) was treated with potassium carbonate in toluene in the presence of I8-crown-6 at 80℃ under Nicolaou's conditions, the intramolecular Wittig-Horner reaction occurred very smoothly, and the 12-membered cyclic enone (11) was isolated in excellent yield, Finally, silyl and benzyl protecting groups were removed with fluoride anion and 2,3-dichloro-5,6-dicyanobenzoquinone, respectively, to afford methynolide (1) in excellent yield. The overall stereoselectivity for the construction of four new chiral centers was very high (89%).
公益社団法人日本薬学会の論文
1987-06-25