Pyridyl methylcyclohexanol

The CH fragment which is linked to the OH group (SH = 5.45) can easily be located in the H and 13C NMR spectra. The chemical shift values Sc =74.2 for C and SH = 3.16 for /f are read from the CH COSY plot. The lH signal at 8H- 3.16 splits into a triplet (11.0 Hz) of doublets (4.0 Hz). The fact that an antiperiplanar coupling of 11 Hz appears twice indicates the diequatorial configuration (trans) of the two substituents on the cyclohexane ring 3. If the substituents were positioned equatorial-axial as in 4 or 5, then a synclinal coupling of ca 4 Hz would be observed two or three times. 

From the HH COSY plot the following HH connectivities A are derived  

In the CH COSY plot it can be established which C atoms are linked with these protons thus the CH skeleton B can readily be derived from A  

Structural elucidation can be completed to give C if the CH multiplicities from the, 3C NMR spectrum and characteristic chemical shift values from the lH and I3C NMR spectra are also taken into account. The CH bond with 8C/SH = 194.019.45, for example, clearly identifies an aldehyde group CH bonds with bciSH = 133.216.08, 158.116.80, 126.715.26 and 133.515.39 identify two CC double bonds of which one (8C/ W =133.1/6.05 and 158.1/6.50) is polarised by the -M effect of the aldehyde group. 

Hence the compound is nona-2,6-dienal. The relative configuration of both CC double bonds follows from the HH coupling constants of the alkene protons in the lH NMR spectrum. The protons of the polarised 2,3-double bond are in trans positions (3Jhh - 15.5 Hz) and those on the 6,7-double bond are in cis positions (3JHH =10.5 Hz). The structure is therefore nona-2-trans-6-cis-dienal, D. 

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