Novel Enantioselective Synthesis of Functionalized Pyridylarsanes by a Chiral Palladium Template Promoted Asymmetric Hydroarsanation Reaction

Authors

  • Fengli Liu,

    1. Division of Chemistry & Biological Chemistry, School ofPhysical & Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
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  • Sumod A. Pullarkat,

    1. Division of Chemistry & Biological Chemistry, School ofPhysical & Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
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  • Yongxin Li,

    1. Division of Chemistry & Biological Chemistry, School ofPhysical & Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
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  • Shuli Chen,

    1. Division of Chemistry & Biological Chemistry, School ofPhysical & Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
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  • Pak-Hing Leung

    1. Division of Chemistry & Biological Chemistry, School ofPhysical & Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
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Abstract

The asymmetric hydroarsanation reactions between diphenylarsane and (E)-1-phenyl-3-(pyridin-2-yl)-2-propenone and (E)-1-methyl-3-(pyridin-2-yl)-2-propenoate have been achieved by use of the organopalladium complex containing ortho-metalated (R)-[1-(dimethylamino)ethyl]naphthalene as the chiral reaction template in high regio- and stereoselectivities under mild conditions. Hydroarsanation of (E)-1-phenyl-3-(pyridin-2-yl)-2-propenone with diphenylarsane generated two stereoisomeric products in the ratio of 3:1 as five-membered As–N bidentate chelates on the chiral naphthylamine palladium template. Using the same chiral metal template, the corresponding hydroarsanation reaction with (E)-1-methyl-3-(pyridin-2-yl)-2-propenoate gave only one product as a six-membered As–N bidentate chelate. The naphthylamine auxiliary could be removed chemoselectively by treatment with concentrated hydrochloric acid to form the corresponding optically pure neutral complexes. Subsequent ligands displacement from the palladium using aqueous potassium cyanide generated the optically pure keto- and ester-functionalized chiral pyridylarsane ligands. The absolute configuration and the coordination properties of the pyridylarsanes have been established by single-crystal X-ray analysis.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

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