Stereoselective Synthesis of All Possible Phosferrox Ligand Diastereoisomers Displaying Three Elements of Chirality:Stereochemical Optimization for Asymmetric Catalysis

Arthurs, Ross A., Hughes, David L. and Richards, Christopher J. (2020) Stereoselective Synthesis of All Possible Phosferrox Ligand Diastereoisomers Displaying Three Elements of Chirality:Stereochemical Optimization for Asymmetric Catalysis. Journal of Organic Chemistry, 85 (7). pp. 4838-4847. ISSN 0022-3263

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Abstract

All four possible diastereoisomers of phosphinofer- rocenyloxazoline (Phosferrox type) ligands containing three elements of chirality were synthesized as single enantiomers. The S-c configured oxazoline moiety (R = Me, i-Pr) was used to control the generation of planar chirality by lithiation, with the alternative diastereoisomer formed by use of a deuterium blocking group. In each case subsequent addition of PhPCl2 followed by o-TolMgBr resulted in a single P-stereogenic diastereoisomer (S-c,S-p,S-phos and S-c,S-p,R-phos,R- respectively). The alternative diastereoisomers were formed selectively by addition of o-TolPCl(2) followed by PhMgBr ((S-c,S-p,R-phos and S-c,S-p,S-phos,S- respectively). Preliminary application of these four ligand diastereoisomers, together with (S-c,S-p) and (S-c,R-p) Phosferrox PPh2, to palladium catalyzed allylic alkylation of trans-1,3-diphenylallyl acetate revealed a stepwise increase/decrease in ee, with the configuration of the matched/matched diastereoisomer as S-c,S-p,S-phos (97% ee).

Item Type: Article
Uncontrolled Keywords: highly enantioselective hydrogenation,diphosphine ligands,allylic alkylation,phosphine oxides,planar chirality,phosphorus,ketones,complexes,efficient,versatile
Faculty \ School: Faculty of Science > School of Chemistry
Faculty of Science > School of Biological Sciences
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Depositing User: LivePure Connector
Date Deposited: 07 May 2020 00:05
Last Modified: 13 Jul 2020 23:59
URI: https://ueaeprints.uea.ac.uk/id/eprint/75051
DOI: 10.1021/acs.joc.9b03342

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