573693-10-4Relevant academic research and scientific papers
A novel total synthesis of the bioactive poly-substituted carbazole alkaloid carbazomadurin A
Hieda, Yuhzo,Choshi, Tominari,Kishida, Sayuri,Fujioka, Haruto,Hibino, Satoshi
, p. 3593 - 3596 (2010)
A new total synthesis of the neuronal cell-protecting carbazole alkaloid carbazomadurin A is described. The key step was an allene-mediated electrocyclic reaction involving an indole [b]-bond for the construction of a highly substituted carbazole ring. The E-alkenyl side chain at the C1 position of carbazole was introduced between O-triflate and alkenyl pinacol borate using the Suzuki-Miyaura reaction. SEM groups were cleaved with TBAF and the formyl group was reduced to provide carbazomadurin A.
Ir-Catalyzed Regio- And Enantioselective Hydroalkynylation of Trisubstituted Alkene to Access All-Carbon Quaternary Stereocenters
Zhang, Su-Lei,Zhang, Wen-Wen,Li, Bi-Jie
supporting information, p. 9639 - 9647 (2021/07/19)
The stereoselective construction of all-carbon quaternary stereocenters, especially acyclic ones, represents an important challenge in organic synthesis. In particular, homopropargyl amides with a quaternary stereocenter β to a nitrogen atom are valuable synthetic intermediates, which could be transformed to diverse chiral structures through alkyne transformations. However, highly enantioselective synthetic methods for homopropargyl amides with a β quaternary stereocenter are extremely rare. We report here unprecedented substrate-directed, iridium-catalyzed enantioselective hydroalkynylations of trisubstituted alkenes to form an acyclic all-carbon quaternary stereocenter β to a nitrogen atom. The hydroalkynylation of enamide occurred with unconventional selectivity, favoring the more hindered reaction site. Homopropargyl amides with β-stereocenters were prepared in high regio- and enantioselectivities. Combined experimental and computational studies revealed the origin of the regio- and enantioselectivities.
Total synthesis of the neuronal cell-protecting carbazole alkaloids carbazomadurin A and (S)-(+)-carbazomadurin B
Hieda, Yuhzo,Choshi, Tominari,Fujioka, Haruto,Hibino, Satoshi
, p. 7391 - 7401 (2013/11/19)
The total syntheses of the neuronal cell-protecting carbazole alkaloids carbazomadurin A and (S)-(+)-carbazomadurin B were achieved. The key step of the synthesis of the polysubstituted carbazole rings included an allene-mediated electrocyclic reaction of the 6π-electron system that involved the indole 2,3-bond. The cleavage of the alkoxy groups of the resulting 3-ethoxy-8-isopropoxycarbazole successfully gave the 3,8-dihydroxycarbazole, which was converted into the 3,8-bis(OSEM)-carbazole (SEM = 2- trimethylsilylethoxymethyl). A Suzuki-Miyaura cross-coupling reaction of the 3,8-bis(OSEM)-carbazole with the corresponding alkenyl pinacol borates afforded the 1-alkenylcarbazoles, which were treated with tetra-n-butylammonium fluoride (TBAF) followed by reduction with NaBH4 to provide carbazomadurin A and (S)-(+)-carbazomadurin B, respectively. The total syntheses of the neuronal cell-protecting carbazole alkaloids carbazomadurin A and (S)-(+)-carbazomadurin B were achieved. The key step of the synthesis of the polysubstituted carbazole rings included an allene-mediated electrocyclic reaction that involved the indole 2,3-bond. Copyright
First total synthesis of the neuronal cell protecting carbazole alkaloid carbazomadurin A by sequential transition metal-catalyzed reactions
Knoelker, Hans-Joachim,Knoell, Jan
, p. 1170 - 1171 (2007/10/03)
The highly oxygenated neuronal cell protecting carbazole alkaloid carbazomadurin A was synthesized in nine steps and 11% overall yield from isovanillic acid.
