Discrimination of pseudo‐meta and pseudo‐para diamino‐octafluoro[2.2]paracyclophanes by ¹H, ¹⁹F, and ¹³C NMR

Abstract

Pseudo-meta and pseudo-para diamino-octafluoro[2.2]paracyclophanes are challenging to separate either by chromatography or recrystallization, but through the use of a mixture of the two isomers, the (1)H, (19)F, and (13)C NMR spectra of these compounds have been fully and unambiguously assigned using (1)H COSY, (1)H-(19)F HOESY, (1)H-(13)C HSQC, (1)H-(13)C HMBC, and (19)F-(13)C HSQC techniques. This permits the easy identification of either of the individual isomers. In addition, the (13)C spectrum of the pseudo-ortho analogue is reported and assigned for the first time. The gem shift effect in this series of bridge-fluorinated paracyclophanes serves to deshield (1)H resonances and shield (13)C.