Chiral ferrocene-based phosphine-imine and sulfur-imine ligands for palladium-catalyzed asymmetric allylic alkylation of cycloalkenyl esters
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چکیده
Chiral ferrocene-based phosphine-imine ligands 1–3 and sulfur-imine ligand 4 were applied in the palladium-catalyzed asymmetric allylic alkylation of cycloalkenyl esters. The results revealed that the substitutents in aryl ring, ferrocenylmethyl and benzyliene position strongly affected the enantioselective induction of phosphine-imine ligands, and the most stereoselective ligand was ferrocenylphosphine-imine 1b with a nitro group in the meta-position of phenyl ring. Under the optimized condition, up to 91% (enantiomeric excesses) e.e. of cyclic alkylation product was obtained by the use of 1b. © 2004 Elsevier B.V. All rights reserved.
منابع مشابه
Ferrocenyl bis-phosphine ligands bearing sulfinyl, sulfonyl or sulfenyl groups: applications in asymmetric hydrogenation and allylic alkylation reactions
A new series of chiral ferrocenyl bis-phosphine ligands have been synthesized. Elements of planar and central chirality have been incorporated into a ferrocene backbone through sulfinyl, sulfonyl and sulfenyl groups at the ortho-position to the phosphines. The effectiveness of these ligands has been demonstrated in Rh-catalyzed hydrogenations and Pd-catalyzed allylic alkylations. 2005 Elsevier ...
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