Total Synthesis of Ascospiroketal A Through a Ag
<sup>I</sup>
‐Promoted Cyclization Cascade
作者:Stanley Chang、Soo Hur、Robert Britton
DOI:10.1002/anie.201408905
日期:2015.1.2
The totalsynthesis of four candidate stereostructures for the marine octaketide ascospiroketal A have been achieved. These concise and highly stereocontrolled syntheses feature a unique AgI‐promotedcyclizationcascade involving an oxetanyl ketochlorohydrin to access the entire tricyclic core of the natural product in one step. These syntheses also establish the full stereochemistry for the ascospiroketal
Total Synthesis and Configurational Assignment of Ascospiroketal A
作者:Stanley Chang、Soo Hur、Robert Britton
DOI:10.1002/chem.201502754
日期:2015.11.9
The totalsynthesis of the marine fungus‐derived natural product ascospiroketal is described. This concise synthesis relies on a unique AgI‐promoted tandem cascadecyclization that provides direct access to the correctly configured tricyclic core of the natural product from a linear precursor. The synthesis of candidate stereostructures of ascospiroketal A allowed for the confident assignment of both
Asymmetric Aldol Reactions Using (<i>S</i>,<i>S</i>)-(<i>+</i>)-Pseudoephedrine-Based Amides: Stereoselective Synthesis of α-Methyl-β-hydroxy Acids, Esters, Ketones, and 1,3-Syn and 1,3-Anti Diols
作者:Jose L. Vicario、Dolores Badía、Esther Domínguez、Mónica Rodríguez、Luisa Carrillo
DOI:10.1021/jo000035h
日期:2000.6.1
reactions is reported. The reaction of (S, S)-(+)-pseudoephedrine-derived propionamide enolates with several aldehydes yielded exclusively one of the four possible diastereomers in good yields, although transmetalation of the firstly generated lithium enolate with a zirconium(II) salt, prior to the addition of the aldehyde, is necessary in order to achieve high syn selectivity. The so-formed syn-alpha-methyl-beta-hydroxy
New Routes to Chiral Evans Auxiliaries by Enzymatic Desymmetrisation and Resolution Strategies
作者:Claudia Neri、Jonathan M. J. Williams
DOI:10.1002/adsc.200303006
日期:2003.6
synthesis using racemic auxiliaries and an enzymatic resolution. Desymmetrisation of N-Boc-protected serinol has been achieved in good yield and high enantiomeric excess using porcine pancreas lipase. This has been exploited in different ways to prepare enantiomerically enriched (4R)- and (4S)-substituted 2-oxazolidinones. In another approach to asymmetric synthesis, starting from a racemic Evans auxiliary
Employing Modular Polyketide Synthase Ketoreductases as Biocatalysts in the Preparative Chemoenzymatic Syntheses of Diketide Chiral Building Blocks
作者:Shawn K. Piasecki、Clint A. Taylor、Joshua F. Detelich、June Liu、Jianting Zheng、Arkady Komsoukaniants、Dionicio R. Siegel、Adrian T. Keatinge-Clay
DOI:10.1016/j.chembiol.2011.07.021
日期:2011.10
Chiral buildingblocks are valuable intermediates in the syntheses of naturalproducts and pharmaceuticals. A scalable chemoenzymaticroute to chiral diketides has been developed that includes the general synthesis of α-substituted, β-ketoacyl N-acetylcysteamine thioesters followed by a biocatalytic cycle in which a glucose-fueled NADPH-regeneration system drives reductions catalyzed by isolated modular