The Regioselective Functionalization Reaction of Unprotected Carbazoles with Donor–Acceptor Cyclopropanes

Abstract

The regioselective functionalization reaction of unprotected carbazoles with donor–acceptor (D–A) cyclopropanes has been demonstrated for the first time. With Sc­(OTf)3 as Lewis acid catalyst, the N–H functionalization of carbazoles takes place through a highly selective nitrogen-initiated nucleophilic ring opening reaction. Significantly, by engaging TfOH as Brønsted acid catalyst, a straightforward C–H functionalization at the 3-position of the unprotected carbazole proceeds via Friedel–Crafts-type addition. This strategy facilitates the diversity-oriented synthesis of carbazole-containing heterocycles and expands the novel application of D–A cyclopropanes.

Donor–Acceptor Biarylcarbazoles as Efficient Host Materials for Solution-Processable High-Performance Phosphorescent Organic Light-Emitting Diodes

“…To introduce D–A functionalities onto the carbazole scaffolds, numerous synthetic approaches have been reported in the literature, which mainly include organometal-catalyzed reactions. − Sekar et al have reported carbazole-derived D−π–A−π–D-based fluorophores via condensation of 2-[1-(9-ethyl-9 H -carbazol-3-yl)­ethylidene]­malononitrile with different aldehydes . Zhao et al have synthesized carbazoles containing D–A cyclopropanes by regioselective N–H/C–H functionalization of carbazole in the presence of TfOH or Sc­(OTf) 3 , but these procedures require either expensive metal catalysts or harsh reaction conditions. Herein, we have explored the simple chemistry of 2 H -pyranones for the synthesis of D–A-functionalized fluorescent carbazole derivatives.…”

The TaCl5-Mediated Reaction of Dimethyl 2-Phenylcyclopropane-1,1-dicarboxylate with Aromatic Aldehydes as a Route to Substituted Tetrahydronaphthalenes

“…In the last 10–15 years, interest in the chemistry of donor–acceptor cyclopropanes (DACs) has grown sharply [ 1 , 2 , 3 , 4 , 5 ]. Their ring-opening transformations are widely used in organic synthesis to assemble various carbo- and heterocyclic compounds, including natural compounds and their analogs [ 6 , 7 , 8 , 9 , 10 ]. Currently, there are a variety of different types of DAC reactions being reported [ 11 ].…”

MgI2-Catalyzed Nucleophilic Ring-Opening Reactions of Donor–Acceptor Cyclopropanes with Indoline-2-thiones

“…The ring-opening reactions of DACs with carbon nucleophiles like indoles, 2-naphthols, electron-rich aromatic compounds, 1,3-dicarbonyl compounds, 6-aminouracils, ferrocene, and TMSCN have been well-established. Moreover, various heteroatom-nucleophiles such as phenols, water, alcohols, amines, azides, and purines as well as thiols have also been applied in the ring-opening processes for the construction of γ-heteroatom functionalized butyric acid derivatives. Ring-opening with sulfur nucleophiles has attracted our attention as it provides straightforward access to γ-thioether functionalized butyric acid derivatives, which could be applied to the construction of methionine analogues and other biologically relevant compounds.…”