Pyridine containing chiral macrocycles: synthesis and their enantiomeric recognition for amino acid derivatives

• Published in: Tetrahedron 2011-08, Vol.67 (34), p.6227-6232
• Main Authors: Deniz, Pınar, Turgut, Yılmaz, Togrul, Mahmut, Hosgoren, Halil
• Format: Article
• Language: English
• Subjects: Amino acids; Binding; Chemistry; Coordination compounds; Derivatives; Esters; Exact sciences and technology; Heterocyclic compounds; Heterocyclic compounds with n hetero atom and also o and/or s, se, te hetero atoms; Heterocyclic compounds with o, s, se, te hetero atom and condensed derivatives; Heterocyclic compounds with only one n hetero atom and condensed derivatives; Hydrochlorides; Inorganic chemistry and origins of life; Ligands; Macrocyclic compounds; Nuclear magnetic resonance; Organic chemistry; Preparations and properties; Titration
• ISSN: 0040-4020; 1464-5416
• DOI: 10.1016/j.tet.2011.06.064

Four novel C 2-symmetric enantiomerically pure, chiral pyridine-18-crown-6 type macrocycles containing lipophilic chains at the stereogenic centers were prepared. The enantioselectivity of the new ligands toward the enantiomers of d-, l-amino acid methyl ester derivatives were also determined by 1H NMR titration method. These novel macrocycles have been showed to be strong complexing agents for d- and l-amino acid methyl ester hydrochloride salts (with K ass up to 13590 M −1 and ∆ G 0 up to 23.3 kJ mol −1 and selectivity ratio: 80:20) by 1H NMR titration methods. These macrocyclic hosts exhibited enantioselective binding towards the d-enantiomer of valine methyl ester hydrochloride with K d / K l up to 5.08 in CDCl 3 with 0.25% CD 3OD. [Display omitted]