2269-93-4

Upstream product

• 917-54-4 methyllithium 
• 75648-66-7 C₂₆H₃₈N₂O₂Si 
• 75648-69-0 (2R,6S,12bS,13R)-13-(tert-Butyl-dimethyl-silanyloxymethyl)-3-eth-(E)-ylidene-12-methyl-1,3,4,7,12,12b-hexahydro-2H,6H-2,6-methano-indolo[2,3-a]quinolizine 
• 75648-68-9 normacusine B, tert-butyldimethylsilyl ether 
• 2673-40-7 perivine 
• 68160-78-1 normacusine B 
• 75648-70-3 1-[(2R,3S,6S,12bS,13R)-13-(tert-Butyl-dimethyl-silanyloxymethyl)-12-methyl-1,3,4,7,12,12b-hexahydro-2H,6H-2,6-methano-indolo[2,3-a]quinolizin-3-yl]-ethanone 
• 77-78-1 dimethyl sulfate 
• 123806-87-1 (6S,10S)-(-)-5-methyl-9-oxo-12-benzyl-6,7,8,9,10,11-hexahydro-6,10-imino-5H-cyclooctaindole 
• 158725-10-1 2,2,4-trimethyl-5-<5,12-dimethyl-9-<<(tert-butyldimethylsilyl)oxy>methyl>-6,7,8,9,10,11-hexahydro-6,10-imino-5H-cyclooctindol-8-yl>-1,3-dioxane 
• 152328-68-2 1-(hydroxymethyl)-2-hydroxy-1-<5,12-dimethyl-9-<<(tert-butyldimethylsilyl)oxy>methyl>-6,7,8,9,10,11-hexahydro-6,10-imino-5H-cyclooctindol-8-yl>propane 

Downstream Products

• 2723-56-0 villalstonine 

Relevant academic research and scientific papers

Stereoselective Access to the Core Structure of Macroline-Type Indole Alkaloids: Total Synthesis of Macroline and Alstomicine

Rapid synthesis of the pentacyclic core structure of macroline-type indole alkaloids, and its application in the total synthesis of macroline and alstomicine is described. The core structure was accomplished in a highly stereocontrolled manner via two key steps, Ireland-Claisen rearrangement and Pictet-Spengler cyclization, commencing from a readily available starting material l-tryptophan, which obviated the need of a particular chiral source as an external catalyst, reagent, or internal auxiliary.

Enantiospecific synthesis of (-)-alstonerine and (+)-macroline as well as a partial synthesis of (+)-villalstonine

The enantiospecific synthesis of (-)-alstonerine (5) and (+)-macroline (8), as well as a partial synthesis of the Alstonia bisindole alkaloid villalstonine (2) has been completed. In addition, a more stable macroline equivalent 9 was prepared. The stereochemistry at C(15) and C(16) in 5 and 8 has been successfully installed by a stereoselective Claisen rearrangement followed by stereospecific hydroboration-oxidation of the exocyclic methylene function at C-16. The E ring in alstonerine 5 was constructed by a regioselective cyclization followed by a novel Swern oxidation under modified conditions [(COCl)2/DMSO/CH2Cl2, -78°C to -10°C/1.5 h; Et3N], whereas the C(20)-C(21) enone system in macroline (8) was generated via a convenient one pot process from the β-diol 45. Condensation of either synthetic (+)-macroline (8) or the macroline equivalent 9 with natural pleiocarpamine 7 in 0.2 N HCl furnished the antiamoebic, antimalarial bisindole alkaloid villalstonine 2. This constitutes the first partial synthesis of any of the Alstonia bisindoles from a synthetically derived indole moiety.

Die absolute Konfiguration von Macrolin, einem Abbauproduct des Alkaloides Villalstonin

The absolute configuration of macroline (1), a degradation product of villalstonine (2), was determined.The chemical degradation of 1 gave a mixture of (-)-(20S)-20,21-hihydro-19-desoxo-macroline (9) and (-)-(20R)-20,21-dihydro-19-desoxo-macroline (10), which was related to the degradation products 9 of (+)-ajmaline (3) and 10 of (+)-isoajmaline (4) of known absolute configuration.Together with the complete relative stereochemistry of 2 the absolute configuration of 2 and of the second moiety of 2, (+)-pleiocarpamine (20), could be derived.Since the absolute configuration of the (-)-6,7-dihydroaspidospermidine moiety of (+)-pycnanthinine has been known already , the structure by Gorman et al. represents the absolute configuration of (+)-pycnanthinine.

An improved total synthesis of (+)-macroline and alstonerine as well as the formal total synthesis of (-)-talcarpine and (-)-anhydromacrosalhine-methine

An intramolecular Pd-catalyzed α-vinylation process is described. This cyclization has been employed for the enantiospecific total synthesis of gram quantities of both (+)-macroline 3 and the macroline equivalent 4. This sequence is compared to the enolate-driven cross-coupling process. The intermediate 4 was also converted into (-)-alstonerine 1 via modification of an intramolecular Tsuji-Wacker oxidation. This sequence resulted in an improved total synthesis of (-)-talcarpine 5 and (-)-anhydromacrosalhinemethine 6 as well.

GENERAL APPROACH FOR THE SYNTHESIS OF MACROLINE/SARPAGINE ALKALOIDS. THE TOTAL SYNTHESIS OF (+)-MACROLINE

(+)-Macroline 1 and a more stable equivalent 2 were synthesized from the tetracyclic ketone 5.The key steps in the synthesis involved a stereoselective Claisen rearrangement followed by hydroboration-oxidation of the resulting olefin 14 to set the correct stereochemistry at C-15 and C-16.