摘要:
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 alpha-substituted carboxylic acids and amino acid derivatives. Enantiodiscrimination of H-1 NMR signals was observed with Delta Delta delta values of up to 0.214 ppm. (C) 2014 Elsevier Ltd. All rights reserved.