Tetrahydro-β-Carbolines and Via Pd-Catalyzed Intramolecular Allylic Alkylation

Significance

1,2,3,4-Tetrahydro-β-carbolines (THBC) are an important class of indole-containing alkaloids with biological and medicinal importance. This report describes the use of a Pd-catalyzed asymmetric allylic alkylation (AAA, Trost reaction) to generate THBC derivatives as well as the syn­thesis of tetrahydro-γ-carbolines (THGCs). A ­thorough screening of ‘privileged’ P,P- and P,N-ligands was done and the optimum conditions employed Li₂CO₃ as the base. Indole substrates with electron-donating and electron-withdrawing groups were tested, with the former giving significantly higher enantiomeric excesses.