Enantioselective Synthesis of a Novel Chiral 2,9‐Disubstituted 1,10‐Phenanthroline and First Applications in Asymmetric Catalysis

Abstract

The asymmetric synthesis of a novel, C2‐symmetric, tetradentate 1,10‐phenanthroline is described; it is based on the stereoselective preparation of two functionalized pyridine subunits, which were subsequently joined through two consecutive carbon–carbon bond‐forming reactions to assemble the heteroaromatic system. Some initial applications of this new chiral ligand in metal‐catalyzed, enantioselective ring‐opening reactions of meso‐epoxides and aminations of β‐keto esters are presented.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Organic Electron Donors as Powerful Single‐Electron Reducing Agents in Organic Synthesis

“…The TDAE-Pd system was recently applied in a multistep synthesis for the homocoupling of iodoindoles or bromopyridines and the TDAE gave better results than metal reductants. [109] In summary, tetrakis(dimethylamino)ethylene is a strong organic electron donor that is able to activate carbon-halogen bonds and thus generate electrophile radicals and stable nucleophilic anions. Hence, either radical or carbanionic reactions can be performed through the judicious choice of substrates and conditions.…”

β-Hydroxy sulfides and their syntheses

“…As an extension to this work, a novel chiral 2,9-disubstituted-1,10-phenanthroline 54 was prepared by the same group and its utility in the enantioselective ring-opening of cis -stilbene oxide with aniline and thiophenol was demonstrated. The reaction provided the corresponding β-hydroxy derivatives in good yields and excellent enantioselectivities ( Scheme 15 ) [ 49 ].…”

Organische Elektronendonoren als leistungsfähige Ein‐Elektronen‐Reduktionsmittel in der organischen Synthese

“…Das TDAE-Pd-System wurde kürzlich in der mehrstufigen Synthese für die Homokupplung von Iodindolen oder Brompyridinen verwendet, und TDAE lieferte bessere Ergebnisse als metallische Reduktionsmittel. [109] Zusammenfassend handelt es sich bei TDAE um einen starken organischen Elektrondonor, der Kohlenstoff-Halogen-Bindungen aktivieren kann, um elektrophile Radikale und stabile nukleophile Anionen zu erzeugen. Somit kçnnen durch eine geschickte Wahl von Substraten und Bedingungen entweder radikalische oder carbanionische Reaktionen durchgeführt werden.…”