The New Appraoch to Antibiotic Carbazomycins. The Formal Total Synthesis of Carbazomycin A and B
摘要:
Deoxycarbazomycin B has been synthesized in a four step sequence. The key reaction has been the thermal electrocyclic reaction of 1,3,5-hexatriene system involving the indole 2,3-bond.
Relay Catalysis of Bismuth Trichloride and Byproduct Hydrogen Bromide Enables the Synthesis of Carbazole and Benzo[α]carbazoles from Indoles and α-Bromoacetaldehyde Acetals
using bismuth trichloride as a catalyst. The reaction was triggered by a bismuth trichloride‐catalyzed Friedel‐Crafts alkylation of these two precursors, which provided a tryptaldehyde intermediate that underwent intramolecular olefination to form the final product. Interestingly, the HBr byproduct generated in the upstream step of the reaction catalyzed the following downstream reaction steps, thus
2‐Alkoxy‐2,3‐dihydrofurans were found to be versatile benzannulation reagents. Indoles can be synthesized in good to excellent yields via the [4+2] annulation of 2‐butoxy‐2,3‐dihydrofuran with pyrroles catalyzed by copper bromide. With the same protocol, carbazoles can also be obtained when indoles are used as starting material with the aid of p‐toluenesulfonic acid. This type of benzannulation reagent
Bismuth(III) Triflate Catalyzed Three-Component Reactions of Indoles, Ketones, and α-Bromoacetaldehyde Acetals Enable Indole-to-Carbazole Transformation
作者:Yanlong Gu、Wenbo Huang、Shaomin Chen、Xin Wang
DOI:10.1021/acs.orglett.8b01707
日期:2018.7.20
A three-component reaction of indoles, α-bromoacetaldehyde acetals, and ketones was developed by using bismuth(III) triflate as the catalyst to realize a straightforward approach for synthesizing carbazole derivatives. The reaction was established mechanistically through the autotandem catalysis of Bi(OTf)3 in the following two steps: (i) Friedel–Crafts-typealkylation of indole with α-bromoacetaldehyde