Syntheses of four enantiomers of 2,3-diendo- and 3-endo-aminobicyclo[2.2.2]oct-5-ene-2-exo-carboxylic acid and their saturated analogues.

Ethyl 2,3-diendo-3-aminobicyclo[2.2.2]oct-5-ene-2-carboxylate ((±)-1) was resolved with O,O'-dibenzoyltartaric acid via diastereomeric salt formation. The efficient synthesis of the enantiomers of 2,3-diendo-3-aminobicyclo[2.2.2]oct-5-ene-2-carboxylic acid ((+)-7 and (-)-7), 3-endo-aminobicyclo[2.2.2]oct-5-ene-2-exo-carboxylic acid ((+)-5 and (-)-5), cis- and trans-3-aminobicyclo[2.2.2]octane-2-carboxylic acid ((+)-6, (-)-6, (+)-8 and (-)-8) was achieved via isomerization, hydrogenation and hydrolysis of the corresponding esters (-)-1 and (+)-1. The stereochemistry and relative configurations of the synthesized compounds were determined by NMR spectroscopy (based on the 3J(H,H) coupling constants) and X-ray crystallography.