Indoles, XII: β-Carbolines from lactones - Synthesis of ligands of the norharmane receptor

Article abstract of DOI:10.1002/ardp.19943271107

Starting from α-ethoxalyl-δ-valerolactone (1) 6-substituted β-carbolines were synthesized in 5 steps to enable investigations at the norharmane binding sites in rat liver and in pig brain. The Pd-catalyzed aromatization of N-benzyl-tetrahydro-β-carbolines with debenzylation was optimized with 5a → 6a and then used for the preparation of other derivatives. Additional hydrogenolyses occur with 5d,h. Bromination of 1a gives 6d which can be transferred to the radioligand ³H-norharmane.