A Three-Component Reaction for the One-Pot Preparation of
β-Amino-α,α-Difluoroketones from Trimethyl(trifluoromethyl)silane (CF3TMS), Acylsilanes and Imines
the acylsilane compared to the imine allows the direct mixing of all the reagents in a three-component, one-pot process. A methodology allowing the direct preparation of β-amino-α,α-difluoroketones from the Ruppert–Prakash reagent (CF3TMS), acyltrimethylsilanes and N-Boc or N-(diphenylphosphinyl)imines is reported. The process, initiated by a catalytic amount of tetra-n-butylammonium difluorotriphenylsilicate
The Mannich Reaction of Malonates with Simple Imines Catalyzed by Bifunctional Cinchona Alkaloids: Enantioselective Synthesis of β-Amino Acids
作者:Jun Song、Yi Wang、Li Deng
DOI:10.1021/ja060716f
日期:2006.5.1
efficient, direct asymmetric Mannichreactions with malonates and N-Boc aryl and alkyl imines by cooperative hydrogen-bonding catalysis with a cinchona alkaloid bearing a thiourea functionality. We have also extended the scope of this reaction to beta-ketoesters. The synthetic value of this new reaction is demonstrated in the establishment of a convergent enantioselective route toward the biologically
Direct Catalytic Asymmetric Mannich-type Reaction of Hydroxyketone Using a Et<sub>2</sub>Zn/Linked-BINOL Complex: Synthesis of Either <i>a</i><i>nti</i>- or <i>s</i><i>yn</i>-β-Amino Alcohols
Full details of a direct catalyticasymmetric Mannich-type reaction of a hydroxyketone using a Et2Zn/(S,S)-linked-BINOL complex are described. By choosing the proper protective groups on imine nitrogen, either anti- or syn-beta-amino alcohol was obtained in good diastereomeric ratio, yield, and excellent enantiomeric excess using the same zinc catalysis. N-Diphenylphosphinoyl (Dpp) imine 3 gave anti-beta-amino
Chiral Ammonium Betaines: A Bifunctional Organic Base Catalyst for Asymmetric Mannich-Type Reaction of α-Nitrocarboxylates
作者:Daisuke Uraguchi、Kyohei Koshimoto、Takashi Ooi
DOI:10.1021/ja8041004
日期:2008.8.1
A chiralammoniumbetaine, an intramolecular ion-pairing quaternary ammonium aryloxide 3, has been designed and its vast potential as an enantioselective organic base catalyst has been successfully demonstrated in the highly enantioselective direct Mannich-type reaction of alpha-substituted alpha-nitrocarboxylates 2 with various N-Boc imines 1. The present study provides a conceptually new approach
combination of the catalytic triad enabled catalyticactivation of acetonitrile as a nucleophile under mild amine-basic conditions. Addition of in situ-generated, Ru-bound, metalated nitrile to aldehydes and imines proceeded smoothly with 2.5-5 mol % Ru complex and 2.5-10 mol % DBU in the presence of 10 mol % NaPF6. Preliminary mechanistic studies suggested a role for each of the three catalytic components