Pd(0)-catalyzed tandem deprotection/cyclization of tetrahydro-β-carbolines on allenes: application to the synthesis of indolo[2,3-a]quinolizidines.

The pallado-catalyzed tandem deprotection/cyclization reaction of enantioenriched N-allyl tetrahydro-β-carbolines on allenes is described. The first step generates in situ a deprotected tetrahydro-β-carboline, which then undergoes a cyclization on the allene function via an intermediate π-allyl Pd(II) derivative. This reaction results in the synthesis of various chiral indolic tetracycles (mainly indolo[2,3a]quinolizidine derivatives) presenting a vinyl function.