162272-99-3Relevant academic research and scientific papers
Synthesis of α-carbolines and β-carbolinones via intramolecular Diels- Alder reactions of 2(1H)-pyrazinones
Tahri, Abdellah,Buysens, Kris J.,Van Der Eycken, Erik V.,Vandenberghe, Didier M.,Hoornaert, Georges J.
, p. 13211 - 13226 (2007/10/03)
2(1H)-Pyrazinones bearing a X-(o-C6H4)-C≡C-R moiety (X=NH, NAc) are shown to undergo an intramolecular cycloaddition-elimination reaction on thermolysis in refluxing bromobenzene yielding α-carbolines or β- carbolinones. The product distribution depends strongly on the substitution pattern of the pyrazinone precursors and the solvent used for thermolysis. A high yield and selective formation of β-carbolinones is possible when heating in tetrahydronaphthalene at reflux. Use of acetic anhydride as solvent facilitated the reaction and made it possible to realise a carbolin(on)e unaccessible by thermolysis in the previously mentioned solvents.
Indoles, XII: β-Carbolines from lactones - Synthesis of ligands of the norharmane receptor
Lehmann,Heineke
, p. 715 - 720 (2007/10/02)
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.
