Preparation and NMR spectra of four isomeric diformyl[2.2]paracyclophanes (cyclophanes 66)

• Ina Dix,
• Henning Hopf,
• Thota B. N. Satyanarayana and
• Ludger Ernst

Beilstein J. Org. Chem. 2010, 6, 932–937, doi:10.3762/bjoc.6.104

• , and were characterized by their spectroscopic data. The individual isomers can now be easily identified from their 1H NMR spectra even if only one of them is present. Keywords: cyclophanes; diformyl[2.2]paracyclophanes; layered compounds; NMR spectroscopy; structure assignment; Introduction

• beginning to attract the attention of other research groups [6][7][10][11][12][13]. Results and Discussion Separation of the diformyl[2.2]paracyclophanes 4 We have separated the isomer mixture 4 by different methods. The easiest way is by middle pressure liquid chromatography (MPLC), which readily affords

• of all isomers and may hence be easily separated. NMR spectra of the diformyl[2.2]paracyclophanes 4 As the 1H and 13C NMR spectra of [2.2]paracyclophane-4-carbaldehyde have previously been fully assigned and, hence, the influence of the substituent upon the 1H and 13C NMR chemical shifts of all