The synthesis of new heterocyclic bridged ring systems. Analogs of tetrahydro-β-carbolines

Abstract New bridged β-carbolines were synthesized via a short synthetic route. The key step of the sequence is a Pictet-Spengler condensation under neutral conditions, employing a cyclic amine and several aldehydes. Using 5,5-diethoxypentanal gave a bridged analog which could be further ring closed to a new pentacyclic system.