Syntheses and biological properties of cysteine-reactive epibatidine derivatives.

The synthesis of epibatidine derivatives modified at the 2-position of the pyridine or pyrimidine rings by reactive functions are described for potential irreversible site-directed coupling reactions on cysteine mutants of neuronal nicotinic acetylcholine receptors. An improved synthesis of the 7-azabicyclo[2,2,1]hepta-2,5-diene key intermediate has been developed to allow reproducible syntheses of the epibatidine derivatives. Binding tests and electrophysiological experiments allowed to select the 2-substituted α-chloroacetamido 13 and the chloropyrimidine derivative 11 as potential site-directed probes for the epibatidine binding site.