[4 + 2] Cyclization or Lossen Rearrangement: Rhodium-Catalyzed Divergent Synthesis of Carboline Derivatives with Anticancer Activity

An unusual rhodium-catalyzed C-H activation/Lossen rearrangement/oxa-Michael addition tandem cyclization has been achieved along with a tunable well-known C-H activation/[4 + 2] annulation, leading to regio-, chemo-, and diastereoselective access to diverse pentacyclic α-carbolines and β-carboline-1-one derivatives in moderate to good yields with significant anticancer activity.

TMSOTf-Promoted Cyclization of Indole-2-methyl-α-aminoketones: Access to 4-Aryl-Substituted β-Carbolines

An efficient method to construct 4-aryl-substituted β-carbolines from indole-2-methyl-α-aminoketones via a TMSOTf-promoted annulation reaction was reported. High yield along with wide substrate scope and functional group tolerance make this reaction applicable to build various highly potential bioactive β-carboline derivatives.

Design, Synthesis, Molecular Docking Study and Biological Evaluation of Novel γ-Carboline Derivatives of Latrepirdine (Dimebon) as Potent Anticancer Agents

A series of novel γ-Carboline derivatives were designed and synthesized using the Suzuki coupling reaction to identify the leads for the activity against cancer. Interestingly, these compounds were tested for their anticancer activity against the cell lines, particularly human cancer cell lines MCF7 (breast), A549 (lung), SiHa (cervix), and Colo-205 (colon). Most of the γ-Carboline derivatives showed potent inhibitory activity in four cancer cell lines, according to in vitro anticancer activity screening. Two compounds, specifically LP-14 and LP-15, showed superior activity in cancer cell lines among the γ-Carboline derivatives from LP-1 to LP-16. Additionally, the compound LP-14, LP-15 and Etoposide carried out molecular docking studies on human topoisomerase II beta in complex with DNA and Etoposide (PDB ID: 3QX3). The docking studies' results showed that the derivative LP-15 was strongly bound with the receptor amino acid residues, including Glu477 and DC8 compared with the marked drug Etoposide.

Access to γ-Carbolines: Synthesis of Isocryptolepine

A new method to synthesize γ-carboline derivatives has been developed starting from 3,5-dibromo-4-pyridinamine by monoarylation using the Suzuki-Miyaura cross-coupling reaction followed by the base-mediated ring closure to pyrrole formation. Synthesis of a series of γ-carboline derivations from the 4-brominated γ-carboline 4a has been achieved by employing various coupling reactions and N-alkylations. This method has been applied for the synthesis of the antimalarial and anticancer natural product isocryptolepine. The photophysical properties of novel γ-carboline derivations are also reported.

Versatile synthesis of functionalized β- and γ-carbolines via Pd-catalyzed C-H addition to nitriles/cyclization sequences

The first example of versatile synthesis of functionalized β-carbolines and γ-carbolines via redox-free Pd-catalyzed C-H addition of indole to nitrile/cyclization sequences is reported. A wide range of functionalized β-carbolines and γ-carbolines can be prepared from readily accessible indoles and nitriles in good to excellent yields under the optimal conditions.