ABSTRACT
An improved preparative four-step synthesis to isoquinuclidine tosylate salt 4 has been demonstrated in 70% overall yield from p-aminobenzoic acid (PABA) 1. Hydrogenation of PABA 1 affords 4-aminocyclohexane carboxylic acid 2 as an 80 : 20 mixture of cis- and trans-isomers. Heating the mixture at 250°C effected epimerization and cyclization to provide the bicyclic lactam 3. Subsequent Red-Al reduction and treatment with tosic acid furnished the desired bicyclic amine, tosylate salt 4.
ACKNOWLEDGMENTS
We thank Drs. Li Li, Thomas Dowling, and Ms. Lisa DiMichele for their help with the analytical assays and NMR studies.