calcimycin and cezomycin

Topics: Bacterial Proteins; Biosynthetic Pathways; Calcimycin; Esters; Mutation; Pyrophosphatases; Streptomyces

Topics: Acyl Coenzyme A; Anti-Bacterial Agents; Bacterial Proteins; Biosynthetic Pathways; Calcimycin; Fatty Acid Synthases; Multigene Family; Streptomyces; Thiolester Hydrolases

A novel acid-promoted rearrangement is disclosed. In the previously unknown transformation, an allyl group migrated to an in situ formed carbocation stabilized by an electron-rich aryl or heteroaryl group, resulting in a stereoselective intramolecular Grob fragmentation. The outcome of the rearrangement observed with an array of substrates can be satisfactorily rationalized using a working hypothesis with the aid of a six-membered transition state similar to those proposed for the anionic oxy-Cope or oxonia-Cope rearrangements, but involving only one instead of two double bonds.

Topics: Acetates; Calcimycin; Diphosphonates; Hydrogen Peroxide; Polyketides; Stereoisomerism

The synthesis of (-)-demethyl (C-11) cezomycin was achieved through an efficient route that features the use of a Kulinkovich reaction to couple two multifunctionality-containing fragments and a cascade of ring opening of cyclopropanol/1,5-hydrogen shift/desilylation-oxidation. The hidden yet undeniable problem of irreproducible specific rotation for this family of compounds was solved by sufficient acidification. The absolute configuration for the natural product was thus established as the mirror image of the synthetic sample.

Topics: Anti-Bacterial Agents; Calcimycin; Hydrogen; Oxidation-Reduction; Stereoisomerism

Topics: Animals; Anti-Bacterial Agents; Calcimycin; Chemical Phenomena; Chemistry; Ethers; Fungi; Gram-Positive Bacteria; Magnetic Resonance Spectroscopy; Mice; Microbial Sensitivity Tests; Soil Microbiology

Topics: Anti-Bacterial Agents; Calcimycin; Culture Media; Ionophores; Magnetic Resonance Spectroscopy; Streptomyces