The first successful example of the direct synthesis of Weinreb amides using catalytic hydroxy-directed dehydrative amidation of carboxylicacids using the diboronic acid anhydride catalyst is described. The methodology is applicable to the concise syntheses of eight α-hydroxyketone natural products, namely, sattabacin, 4-hydroxy sattabacin, kurasoins A and B, soraphinols A and B, and circumcins B
Asymmetric hydrogenation of α-keto Weinreb amides has been realized with [Ru((S)-Sunphos)(benzene)Cl]Cl as the catalyst and CeCl3·7H2O as the additive. A series of enantiopure α-hydroxy Weinreb amides (up to 97% ee) have been obtained. Catalytic amount of CeCl3·7H2O is essential for the high reactivity and enantioselectivity and the ratio of CeCl3·7H2O to [Ru((S)-Sunphos)(benzene)Cl]Cl plays an important role in the hydrogenation reaction.
A new type of tridentate chiral spiro aminophosphine−oxazoline ligands (SpiroOAP) have been synthesized through four steps. The SpiroOAP ligands are highly efficient for the asymmetric hydrogenation of α‐keto amides, providing a variety of synthetically useful α‐hydroxy amides with excellent enantioselectivity (up to 98% ee) and turnover numbers (up to 10,000).
Palladium‐Catalyzed Enantioselective Isodesmic C–H Iodination of Phenylacetic Weinreb Amides
作者:Hang Wang、Chunlin Zhou、Zezhong Gao、Shangda Li、Gang Li
DOI:10.1002/anie.202300905
日期:——
Isodesmic reactions represent mild alternatives to other chemical transformations that require harsh oxidizing agents or highly reactive intermediates. However, enantioselective isodesmic C−Hfunctionalization is unknown. Herein, an unprecedented highly enantioselective isodesmic C−Hfunctionalization to access chiral iodinated phenylacetic Weinrebamides via desymmetrization and kinetic resolution
Highly Diastereoselective Intramolecular Asymmetric Oxidopyrylium-olefin [5 + 2] Cycloaddition and Synthesis of 8-Oxabicyclo[3.2.1]oct-3-enone Containing Ring Systems
作者:Arun K. Ghosh、Monika Yadav
DOI:10.1021/acs.joc.1c00600
日期:2021.6.18
asymmetric intramolecular oxidopyrylium-alkene [5 + 2]-cycloaddition reaction which resulted in the synthesis of functionalized tricyclic ring systems containing an 8-oxabicyclo[3.2.1]octane core. Intramolecular cycloaddition constructed two new rings, three new stereogenic centers, and provided a tricyclic cycloadduct with high diastereoselectivity and isolated yield. We incorporated an α-chiral center