Ring-expanded chiral rhombamine macrocycles for efficient NMR enantiodiscrimination of carboxylic acid derivatives

Novel 46-membered chiral rhombamine macrocycles (R,R,R,R)-8a and 8b were synthesized by [2+2] cyclocondensation reactions of (R,R)-1,2-diaminocyclohexane with the corresponding dialdehydes and subsequent reduction with NaBH4. The X-ray crystal structure of 1:4 dioxane complex with (R,R,R,R)-8a indic...

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Bibliographic Details
Published in:Tetrahedron: asymmetry 2014-04, Vol.25 (8), p.602-609
Main Authors: Tanaka, Koichi, Iwashita, Tomoharu, Sasaki, Chihiro, Takahashi, Hiroki
Format: Article
Language:English
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Summary:Novel 46-membered chiral rhombamine macrocycles (R,R,R,R)-8a and 8b were synthesized by [2+2] cyclocondensation reactions of (R,R)-1,2-diaminocyclohexane with the corresponding dialdehydes and subsequent reduction with NaBH4. The X-ray crystal structure of 1:4 dioxane complex with (R,R,R,R)-8a indicated a rhombus conformation of the chiral macrocycle. Compounds (R,R,R,R)-8a and 8b were tested as chiral shift reagents for a wide range of α-substituted carboxylic acids and amino acid derivatives. Enantiodiscrimination of 1H NMR signals was observed with ΔΔδ values of up to 0.214ppm.
ISSN:0957-4166
1362-511X
DOI:10.1016/j.tetasy.2014.03.009