title: Studies on catalytic enantioselective total synthesis of caprazamycin B: construction of the western zone.
abstract: We describe a simple and convenient synthesis of the western zone of caprazamycin B using two catalytic asymmetric reactions as key elements of our approach. Desymmetrization of 3-methylglutaric anhydride with the (S)-Ni(2)-(Schiff base) complex as a catalyst furnished the chiral hemiester, and a thioamide-aldol reaction with mesitylcopper, (R,R)-Ph-BPE, and 2,2,5,7,8-pentamethylchromanol as a catalyst furnished the β-hydroxy thioamide in good yield and enantioselectivity. On further transformation, the thioamide functionality was converted to the corresponding β-hydroxy ester. Finally, a convergent synthesis of the western zone of caprazamycin B was achieved by connecting the hemiester, the β-hydroxy ester, and the 2,3,4-tri-O-methyl-l-rhamnose fragments.
authors.affiliation: Institute of Microbial Chemistry (BIKAKEN), Tokyo, 3-14-23 Kamiosaki, Shinagawa-ku, Tokyo 141-0021, Japan.
authors.forename: Purushothaman
authors.initials: P
authors.lastname: Gopinath
authors.forename: Takumi
authors.initials: T
authors.lastname: Watanabe
authors.forename: Masakatsu
authors.initials: M
authors.lastname: Shibasaki
mesh_terms: D002384:Catalysis; D008055:Lipids / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D009705:Nucleosides / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D008055:Lipids; D009705:Nucleosides; C476914:caprazamycin B