Amino acids and peptides. XIII. A new approach to the biogenetictype, asymmetric synthesis of indole and isoquinoline alkaloids by 1,3-transfer of asymmetry.

Antiproliferative activity of arborescidine alkaloids and derivatives

“…Using our approach in the target synthesis of complex indole alkaloids and their synthetic analogues, we undertook the synthesis of a simple indole alkaloid, (S)-(À)-1,2,3,4,6,7,12,12b-octahydroindolo[2,3-a]quinolizine 1b (desbromoarborescidine A), the main constituent of Dracontomelum mangiferum B1 [23,24].…”

Asymmetric Reduction of Prochiral Cyclic Imines to Alkaloid Derivatives by Novel Asymmetric Reducing Reagent in THF or under Solid-State Conditions

“…Addition of reducing agent 2 to prochiral cyclic imines 3 or 5 gave the alkaloids 4 or 6 in 75−80% yield. The enantiomeric excess of 4 or 6 was determined to be 65−75% from 1 H NMR chiral nonracemic shift studies using (−)-( R )- N -(3,5-dinitrobenzoyl)-α-phenylethylamine as a chiral shift reagent 3 and comparing the optical rotation of 4 or 6 with known compounds. ,− To determine the enantiomeric excess of the product, we mixed it with 1 equiv of chiral shift reagent in an NMR tube. The 1 H NMR spectrum of pure 4b showed a singlet (δ 4.96 (s, 1 H)).…”

Chiral Lewis Acid-Mediated Enantioselective Pictet−Spengler Reaction of Nb-Hydroxytryptamine with Aldehydes

“…The authentic samples ( S )- 10 , [α] 24 D −16.4 ( c 0.39, EtOH), and ( S )- 21 , [α] 26 D −55.4 ( c 0.41, MeOH), were synthesized from l -tryptophan methyl ester with benzaldehyde and isovaleraldehyde, respectively, according to the synthesis of ( S )- 20 described in the literature . Details of these syntheses will be reported separately.…”