title: Total Synthesis of Purported Cephalosporolides H and I, Penisporolide B, and Their Stereoisomers.
abstract: Development of a unified, bioinspired synthetic strategy to access four possible diastereomers of unique 2,2-dimethyl-[5,5]-spiroacetal-cis-fused-γ-lactone (Me2SAFL) is reported, featuring pyridinium chlorochromate (PCC)-promoted oxidative ring expansion of β-hydroxy cyclic ethers and dehydrative ring-contraction rearrangement of 10-membered lactones. Synthetic utility of this strategy was demonstrated by total syntheses of 12 Me2SAFLs, corresponding to the purported cephalosporolide H (CesH), cephalosporolide I (CesI), and penisporolide B (PenB) and their possible diastereomers. Comprehensive NMR data analysis suggested that the tricyclic Me2SAFL core of CesH, CesI, and PenB should be revised to the same relative (3R*, 4R*, 6S*, 9R*) configuration and that the side chains required an unknown constitutional structure revision.
authors.affiliation: Department of Chemistry, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Chemistry, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong, China.
authors.forename: Rongbiao
authors.initials: R
authors.lastname: Tong
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000138:chemical synthesis; D007783:Lactones / Q000138:chemical synthesis*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D015394:Molecular Structure; D013141:Spiro Compounds / Q000138:chemical synthesis*; D013237:Stereoisomerism
chemical_list: D007783:Lactones; D013141:Spiro Compounds; C523374:cephalosporolide H; C523375:cephalosporolide I; C520917:penisporolide B; D015107:4-Butyrolactone