Molecules (May 2012)

Synthesis and Characterization of Some New <em>C<sub>2</sub></em> Symmetric Chiral Bisamide Ligands Derived from Chiral Feist’s Acid

  • Assem Barakat,
  • Zeid Abdullah Al-Othman,
  • Ahlam F. Al-Salhoob,
  • Abdullah M. A. Al Majid,
  • Mohammad Shahidul Islam

DOI
https://doi.org/10.3390/molecules17055550
Journal volume & issue
Vol. 17, no. 5
pp. 5550 – 5563

Abstract

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The hemilabile chiral <em>C<sub>2</sub></em> symmetrical bidentate substituted amide ligands (1<em>R</em>,2<em>R</em>)-<strong>5<sub>a-d</sub></strong> and (1<em>S</em>,2<em>S</em>)-<strong>6<sub>a-d</sub></strong> were synthesized in quantitative yield from (1<em>R</em>,2<em>R</em>)-(+)-3-methylenecyclo-propane-1,2-dicarboxylic acid (1<em>R</em>,2<em>R</em>)-<strong>3</strong> and (1<em>S</em>,2<em>S</em>)-(-)-3-methylene-cyclopropane-1,2-dicarboxylic acid (1<em>S</em>,2<em>S</em>)-<strong>3</strong>, in two steps, respectively. The chiral Feist’s acids (1<em>R</em>,2<em>R</em>)-<strong>3</strong> and<strong> </strong>(1<em>S</em>,2<em>S</em>)-<strong>3</strong> were obtained in good isomeric purity by resolution of <em>trans</em>-(±)-3-methylene-cyclopropane-1,2-dicarboxylic acid from an 8:2 mixture of <em>tert</em>-butanol and water, using (<em>R</em>)-(+)-<em>α</em>-methylbenzyl amine as a chiral reagent. This process is reproducible on a large scale. All these new synthesized chiral ligands were characterized by <sup>1</sup>H-NMR, <sup>13</sup>C-NMR, IR, and mass spectrometry, as well as elemental analysis and their specific rotations were measured. These new classes of <em>C<sub>2</sub></em> symmetric chiral bisamide ligands could be of special interest in asymmetric transformations.

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