Enantioselective synthesis of some tetrahydroisoquinoline and tetrahydro-β-carboline alkaloids

摘要: Abstract Four alkaloids: (R)-(+)-cryspine A 5, (R)-(+)-octahydroindolo[2,3-a]quinolizidine 8, (R)-(+)-harmicine 19 and (R)-(+)-desbromoarborescidine 22 were prepared via the asymmetric transfer hydrogenation reaction of a prochiral enamine (iminium salt). The enantiomeric excesses isolated alkaloids determined from their 1H NMR spectra measured in presence (+)-(R)-tert-butylphenylphosphinothio(seleno)ic acids as chiral solvating agents. absolute configurations at newly created stereogenic carbon atoms confirmed, all cases, by X-ray crystallography.