Formal Total Synthesis of the Polyketide Macrolactone Narbonolide
作者:Lakshmanan Venkatraman、Courtney C. Aldrich、David H. Sherman、Robert A. Fecik
DOI:10.1021/jo050924a
日期:2005.9.1
An improved synthesis of (3S)-3-dihydronarbonolide is reported that constitutes a formal total synthesis of the 14-membered macrolactone antibiotic narbonolide. The key step was an intramolecular Nozaki−Hiyama−Kishi coupling to accomplish macrocyclization in improved yield. The high level of convergence will also allow us to rapidly synthesize narbonolide analogues for the study of enzymes in the pikromycin
Synthesis and Biochemical Analysis of Complex Chain-Elongation Intermediates for Interrogation of Molecular Specificity in the Erythromycin and Pikromycin Polyketide Synthases
作者:Jonathan D. Mortison、Jeffrey D. Kittendorf、David H. Sherman
DOI:10.1021/ja9060596
日期:2009.11.4
The 6-deoxyerythronolide B synthase (DEBS) and pikromycin (Pik) polyketide synthase (PKS) are unique multifunctional enzyme systems that are responsible for the biosynthesis of the erythromycin and pikromycin 14-membered ring aglycones, respectively. Together, these natural product biosynthetic systems provide excellent platforms to examine the fundamental structural and catalytic elements that govern polyketide assembly, processing, and macrocyclization. In these studies, the native pentaketide intermediate for DEBS was synthesized and employed for in vitro chemoenzymatic synthesis of macrolactone products in engineered monomodules Ery5, Ery5-TE, and Ery6. A comparative analysis was performed with the corresponding Pik module 5 (PikAIII) and module 6 (PikAIV), dissecting key similarities and differences between these highly related PKSs. The data revealed that individual modules in the DEBS and Pik PKSs possess distinctive molecular selectivity profiles and suggest that substrate recognition has evolved unique characteristics in each system.
COMBINATORIAL POLYKETIDE LIBRARIES PRODUCED USING A MODULAR PKS GENE CLUSTER AS SCAFFOLD