Efficient NMR chiral discrimination of carboxylic acids using rhombamine macrocycles as chiral shift reagent

Abstract

Chiral rhombamine macrocycles 1a– b were prepared by a [2+2]cyclocondensation reaction of ( R, R)-1,2-diaminocyclohexane with corresponding dialdehydes and were found to be useful as NMR chiral shift reagents for the determination of enantiomeric purity and the absolute configuration of a wide range of carboxylic acid and amino acid derivatives.