1-Substituted β-carboline-3-carboxylates with high affinities to the benzodiazepine recognition site

Naturally occurring derivatives of beta-carboline-3-carboxylic acid bearing acetyl or vinyl groups at C-1 were prepared by Pd-catalyzed cross-coupling reactions of methyl 1-chloro-beta-carboline-3-carboxylate with appropriate organostannanes. Esters with chloro or acetyl groups at C-1 showed high affinity for the brain benzodiazepine recognition site. Thus, in contrast to 1-alkyl and 1-aryl analogs, these beta-carboline-3-carboxylates with electron-withdrawing substituents at C-1 show high affinities.