An organocatalyticasymmetricformal [3 + 2] cycloaddition of enynones with N-hydroxylamines has been described. A newly designed multifunctional organocatalyst was found to be highly effective, and the method allowed the synthesis of a variety of 2,3-dihydroisoxazoles in good yields with excellent enantioselectivity.
Structure−Activity Relationships of <i>N</i>-Hydroxyurea 5-Lipoxygenase Inhibitors
作者:Andrew O. Stewart、Pramila A. Bhatia、Jonathan G. Martin、James B. Summers、Karen E. Rodriques、Michael B. Martin、James H. Holms、Jimmie L. Moore、Richard A. Craig、Teodozyj Kolasa、James D. Ratajczyk、Hormoz Mazdiyasni、Francis A. J. Kerdesky、Shari L. DeNinno、Robert G. Maki、Jennifer B. Bouska、Patrick R. Young、Carmine Lanni、Randy L. Bell、George W. Carter、Clint D. W. Brooks
DOI:10.1021/jm9700474
日期:1997.6.1
The discovery of second generation N-hydroxyurea 5-lipoxygenase inhibitors was accomplished through the development of a broad structure-activity relationship (SAR) study. This study identified requirements for improving potency and also extending duration by limiting metabolism. Potency could be maintained by the incorporation of heterocyclic templates substituted with selected lipophilic substituents. Duration of inhibition after oral administration was optimized by identification of structural features in the proximity of the N-hydroxyurea which correlated to low in vitro glucuronidation rates. Furthermore, the rate of in vitro glucuronidation was shown to be stereoselective for certain analogs. (R)-N-[3-[5-(4-Fluorophenoxy)-2-furyl]-1-methyl-2-propynyl]-N-hy- droxyurea (17c) was identified and selected for clinical development.
Phase-transfer catalysis for the synthesis of hydroxylamines from oximes using benzyltriethylammonium borohydride in methanol and under solid-phase conditions
作者:Mannathusamy Gopalakrishnan、Thirunavukkarasu Anandabaskaran、Purusothaman Sureshkumar、Jayaraman Thanusu、Arumugam K. Kumaran、Vijayakumar Kanagarajan
DOI:10.1070/mc2006v016n01abeh002213
日期:2006.1
Effective phase-transfer catalysis methodologies for the reduction of oximes to hydroxylamines by a selective and versatile reducing agent, benzyltriethylammonium borohydride (BTEABH), in methanol and under solid-phase conditions are presented.