Formal Synthesis of Bioactive Indole Alkaloids Eburnamonine, Eburnaminol, and Vindeburnol

Starting from (±)-3-acetoxyglutarimide, diastereoselective formal synthesis of indole alkaloids (±)-eburnamonine, (±)-eburnaminol, and (±)-vindeburnol have been demonstrated via a common intermediate (±)-1-hydroxy-12-tosyl-2,3,6,7,12,12b-hexahydroindolo[2,3- a ]quinolizin-4(1 H )-one in very good overall yields. The acetoxy group from (±)-3-acetoxyglutarimide was first used to induce the diastereoselectivity and also as a latent source of ketone carbonyl group. The ste­reo­selective eliminations, reductions, and intramolecular cyclizations were the involved key steps.