A New Platform for Designing Ligands for Asymmetric Induction in Allylic Alkylations

Authors


  • We thank the National Science Foundation and the National Institutes of Health, General Medical Sciences, for their generous support of our programs. A postdoctoral fellowship for B. B. was provided by the BASF Aktiengesellschaft, a stipend for S. P. by the Studienstiftung des Deutschen Volkes, and a predoctoral fellowship for J. Z. by INTEVEP (Venezuela). Mass spectra were provided by the Mass Spectrometry Facility, University of California-San Fransisco, which is supported by the NIH Division of Research Resources. Johnson Matthey Alfa Aesar provided palladium salts under a loan program.

Abstract

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Simply inverting the orientation of the amide function as in 1 compared to that of the ligand series derived from 2-diphenylphosphinobenzoic acid affects the enantiomeric discriminating step in the Pd-catalyzed nucleophilic alkylation of meso-1,4-dihydroxy-2-cycloalkenes. In reactions such as this, the bond-making or -breaking event occurs outside the coordination sphere of the metal. The chiral scaffold of the ligand is connected to the metal atom by a linker (here 2-diphenylphosphinoaniline), and the preferred conformation of the catalysts provides “chiral spaces” for the substrate–a conclusion supported by X-ray crystallography.

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