Preparation of 2,4-Disubstituted Cyclopentenones by Enantioselective Iridium-Catalyzed Allylic Alkylation: Synthesis of 2′-Methylcarbovir and<i>TEI-9826</i>
作者:Pierre Dübon、Mathias Schelwies、Günter Helmchen
DOI:10.1002/chem.200800495
日期:2008.7.28
A broadly applicable synthesis of chiral 2- or 2,4-substituted cyclopent-2-enones has been developed by combining asymmetric iridium-catalyzedallylic alkylation reactions and ruthenium-catalyzed ring-closing metathesis. Enantiomeric excesses (ee values) in the range of 95-99 % ee have been achieved. This method offers a straightforward access to biologically active prostaglandins of the PGA type.
Regio- and Enantioselective <i>N</i>-Allylations of Imidazole, Benzimidazole, and Purine Heterocycles Catalyzed by Single-Component Metallacyclic Iridium Complexes
作者:Levi M. Stanley、John F. Hartwig
DOI:10.1021/ja902243s
日期:2009.7.1
Kinetic studies on the allylation of benzimidazole catalyzed by metallacyclic iridium-phosphoramidite complexes, in combination with studies on the deactivation of these catalysts in the presence of heterocyclic nucleophiles, provide insight into the effects of the structures of the phosphoramidite ligands on the stability of the metallacyclic catalysts. The data obtained from these studies have led to
Carbocycles with > 90% ee were prepared via Ir-catalysed asymmetric allylic alkylation/ring closing metathesis sequences or enantioselective Ir-catalysed intramolecular allylic alkylations.