Synthesis of meta- and paracyclophanes containing unsaturated amino acid residues

7.7], 8.8], 9.9] and 13.13] Paracyclophanes and 9.9] and 13.13] metacyclophanes containing two unsaturated amino acid residues have been synthesised. An X-ray crystallographic study of three of the paracyclophanes and molecular modelling of two paracyclophanes and two metacyclophanes revealed two main structural types. The ‘staggered’ structure appears to be favoured by longer hydrocarbon chains, whilst the ‘barrel’ structure appears to be more accessible to compounds containing shorter hydrocarbon chains. The 9.9] paracyclophane has been hydrogenated and deprotected to give a saturated amino acid, and an alternative approach to key aldehydes is reported.