Rational design of cyclopropane-based chiral PHOX ligands for intermolecular asymmetric Heck reaction
نویسندگان
چکیده
A novel class of chiral phosphanyl-oxazoline (PHOX) ligands with a conformationally rigid cyclopropyl backbone was synthesized and tested in the intermolecular asymmetric Heck reaction. Mechanistic modelling and crystallographic studies were used to predict the optimal ligand structure and helped to design a very efficient and highly selective catalytic system. Employment of the optimized ligands in the asymmetric arylation of cyclic olefins allowed for achieving high enantioselectivities and significantly suppressing product isomerization. Factors affecting the selectivity and the rate of the isomerization were identified. It was shown that the nature of this isomerization is different from that demonstrated previously using chiral diphosphine ligands.
منابع مشابه
Access to enantioenriched 2,3- and 2,5-dihydrofurans with a fully substituted C2 stereocenter by Pd-catalyzed asymmetric intermolecular Heck reaction† †Electronic supplementary information (ESI) available: Experimental procedures, characterization of all new compounds, VCD studies and spectral data. See DOI: 10.1039/c5sc01460c Click here for additional data file.
During the past decades, building on the seminal contributions of Overman and Shibasaki, the asymmetric intramolecular Heck reaction has been successfully applied in natural product synthesis to install tertiary and quaternary stereocenters. In stark contrast, the intermolecular version of this asymmetric transformation has not reached the same level of development and its synthetic utility rem...
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