A novel TFA-mediated cyclo-dimerization of 1-substituted 3-alkenylindole derivatives to cyclopent[b]indoles

Ga(OTf)3-Catalyzed Temperature-Controlled Regioselective Friedel-Crafts Alkylation of Trifluoromethylated 3-Indolylmethanols with 2-Substituted Indoles: Divergent Synthesis of Trifluoromethylated Unsymmetrical 3,3'-and 3,6'-Bis(indolyl)methanes

An unprecedented Ga(OTf)₃-catalyzed, temperature-controlled regiodivergent alkylation of 2-substituted indoles with trifluoromethylated 3-indolylmethanols is described that provides structurally diverse unsymmetrical 3,3'- and 3,6'-bis(indolyl)methanes with a CF₃-containing quaternary carbon center in good to excellent yields under mild conditions. In addition, this present protocol could be successfully extended to the synthesis of difluoromethylated 3,3'- and 3,6'-bis(indolyl)methanes with excellent efficiency.

E/Z isomerization, solvatachromism and aggregation-induced emission enhancement of donor–acceptor type oligo(p-phenylene vinylene)s

A donor–acceptor molecule, PICNDSB, with cyclopenta[b]indole as the donor and (1,4-phenylene)bis(3-phenylacrylonitrile) as the acceptor, is designed and synthesized. PICNDSB shows typical aggregation-induced emission characteristics. The photoluminescence quantum yield of PICNDSB in dilute THF was only 0.7% and reaches 51.4% in the solid state. Compared with its analogue CzCNDSB, PICNDSB possesses stronger intramolecular charge transfer properties, as revealed from CV measurements, theoretical calculations, and their fluorescence behaviors. Correspondingly, the relatively more efficient electron-donating terminal group of cyclopenta[b]indole endows the molecule with a much higher two-photon absorption cross section of 1286 GM compared to CzCNDSB (357 GM).

C3-Selective alkenylation of N-acylindoles with unactivated internal alkynes by cooperative nickel/aluminium catalysis

Highly regio- and stereoselective alkenylation of N-acylindoles with unactivated internal alkynes has been accomplished by cooperative nickel/aluminium catalysis to afford C3-alkenylated indoles.

Synthesis of polysubstituted cyclopenta[b]indoles via relay gold(i)/Brønsted acid catalysis

A relay gold(i)/Brønsted acid catalyzed one-pot cyclopentannulation of indoles has been achieved starting from easily accessible 1-(2-aminophenyl)prop-2-ynols and readily available 1,3-dicarbonyls.

Exploring stereoselectivity of 3-indolyl cyclopent[b]indoles: a parallel synthesis and anti-EGFR study on human cancer cells

We synthesized a series of novel 3-indolyl cyclopent[b]indoles by trifluoroacetic acid mediated cyclodimerizations. The reaction showed high stereoselectivity and moderate to good yields. The influencing factors for stereoselectivity were systematically analyzed and a stepwise reaction mechanism was proposed. The cell viability tests in two colon and two lung cancer cell lines indicated the 1-benzyl-2-phenyl-group in 3-indolyl cyclopent[b]indoles was critical for the observed lower IC₅₀s in these compounds. Western blot analysis demonstrated that the compound inhibited the expression and phosphorylation of EGFR through altered HSP90 expression. Further cell cycle and cell cycle check point protein analyses showed expected anti-cellular proliferation and cell cycle arresting properties associated with suppressed EGFR expression and phosphorylation. These data revealed a novel molecular mechanism explaining the observed cytotoxicities for these compounds.