Enantioselective Formation of a Dynamic Hydrogen-Bonded Assembly Based on the Chiral Memory Concept

Ishi-i, Tsutomu and Crego Calama, Mercedes and Timmerman, Peter and Reinhoudt, David N. and Shinkai, Seiji (2002) Enantioselective Formation of a Dynamic Hydrogen-Bonded Assembly Based on the Chiral Memory Concept. Journal of the American Chemical Society, 124 (49). pp. 14631-14641. ISSN 0002-7863

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Abstract:	In this paper, we report the enantioselective formation of a dynamic noncovalent double rosette assembly 1a3·(CYA)6 composed of three 2-pyridylcalix[4]arene dimelamines (1a) and six butylcyanuric acid molecules (BuCYA). The six 2-pyridyl functionalities of the assembly interact stereoselectively with chiral dicarboxylic acids 3a-e via two-point hydrogen-bonding interactions. One of the two enantiomeric assemblies (P- or M-) 1a3·(CYA)6 is formed in excess as the result of the complexation of the chiral diacids, resulting in formation of optically active assemblies. The complexations with dibenzoly tartaric acids D-3a and L-3a (3 equivalent), respectively, leading to the formation of diastereomeric assemblies (P)-1a3·(BuCYA)6·(D-3a)3 and (M)-1a3·(BuCYA)6·(L-3a)3 with 90% diastereomeric excess. The diastereomeric excess in (M)-1a3·(BuCYA)6·(L-3a)3 is "memorized" when L-3a is removed by precipitation with ethlylenediamine (EDA). The assembly (M)-1a3·(BuCYA)6 is still optically active (90% enantiomeric excess), although none of its individual components are chiral. (M)-1a3·(BuCYA)6 has a high kinetic stability toward racemization (Ea = 119 kJ mol-1, half-life of (M)-1a3·(BuCYA)6 is ca. 1 week at 20°C).
Item Type:	Article
Copyright:	© 2002 American Chemical Society
Research Group:	Supramolecular Chemistry and Technology (SMCT)
Link to this item:	http://purl.utwente.nl/publications/38094
Official URL:	http://dx.doi.org/10.1021/ja0207302
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