Synthesis of rigid and C₂-symmetric 18-crown-6 type macrocycles bearing diamide–diester groups: enantiomeric recognition for α-(1-naphthyl)ethylammonium perchlorate salts

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• 作者：Deniz Barı ; &#x15f ; Sevil &#x15e ; eker ; Halil Ho&#x15f ; gö ; ren ; Mahmut Toğ ; rul
• 刊名：Tetrahedron: Asymmetry
• 出版年：2010
• 出版时间：4 August 2010
• 年：2010
• 卷：21
• 期：15
• 页码：1893-1899
• 全文大小：565 K

文摘

A series of rigid and chiral C₂-symmetric 18-crown-6 type macrocycles (S,S)-4, (S,S)-5, (S,S)-6 and (R,R)-2 bearing diamide–ester groups were synthesized. The binding properties of these macrocycles were examined for α-(1-naphthyl)ethylammonium perchlorates salts by an ¹H NMR titration method. Taking into account the host employed, important differences were observed in the K_a values of (R)- and (S)-enantiomers of guests for macrocycles (S,S)-4 and (S,S)-6, K_S/K_R = 3.6, and K_S/K_R = 0.1 (K_R/K_S = 10.3) ΔΔG = 3.19 and ΔΔG = −5.77 kJ mol⁻¹, respectively. The results indicated excellent enantioselectivity of macrocyclic (S,S)-6 towards the enantiomers of α-(1-naphthyl)ethylammonium perchlorate salts.