Bismuth(III)-Catalyzed Oxidative Cross-Coupling of 3-Hydroxycarbazoles with Arenols under an Oxygen Atmosphere

A Bi(OTf)3-catalyzed oxidative cross-coupling reaction of 3-hydroxycarbazoles with arenols was developed under mild conditions. Both substrates were used in a 1:1 molar ratio in the presence of a catalytic amount of Bi(OTf)3. The reaction was carried out under an oxygen atmosphere at 30 °C to afford C1-symmetric hydroxybiaryls in good yields (up to 94%) with high chemo- and regioselectivity.

Synthesis of N-Arylindoles from 2-Alkenylanilines and Diazonaphthalen-2(1H)-ones through Simultaneous Indole Construction and Aryl Introduction

In this paper, an efficient synthesis of N-arylindoles through the cascade reaction of 2-alkenylanilines with diazonaphthalen-2(1H)-ones is presented. Mechanistically, this reaction involves the generation of a Ru-carbene complex from diazonaphthalen-2(1H)-one, followed by carbene N-H bond insertion with 2-alkenylaniline, intramolecular cyclization, and oxidative aromatization. In this reaction, the Ru(II) complex acts as a multifunctional catalyst to promote not only the carbene formation but also the intramolecular cyclization and the dehydrogenative aromatization. Meanwhile, air acts as a green and cost-effective oxidant. To our knowledge, this is the first example in which N-arylindoles were synthesized through simultaneous introduction of the N-aryl unit and construction of the indole scaffold. Notable advantages of this method include readily accessible and halide-free substrates, additive-free reaction conditions, good efficiency, excellent atom economy, and compatibility with diverse functional groups. In addition, the utility of the product thus obtained was showcased by its diverse structural transformations.

Borane-Catalyzed Carbazolation Reactions of Aryldiazoacetates

Herein, we report on the tris(pentafluorophenyl)borane-catalyzed reaction of carbazole heterocycles with aryldiazoacetates. We could demonstrate that selective N-H functionalization occurs in the case of an unprotected carbazole, other N-heterocycles, and secondary amines in good yields. In contract, the protected carbazole undergoes C-H functionalization at the C-3 position in a good yield. The application of both approaches was studied in 41 examples with up to a 97% yield.

Construction of Partially Protected Nonsymmetrical Biaryldiols via Semipinacol Rearrangement of o-NQM Derived from Enynones

The construction of partially protected nonsymmetrical biaryldiols catalyzed by AgBF₄ has been achieved. The approach facilitates the formation of two new aryl rings and the introduction of two hydroxyl groups (one free and one TBS-protected) via the o-NQM generation/semipinacol rearrangement cascade, featuring high atom- and step-economy to afford a diverse array of partially protected nonsymmetrical biaryldiols under mild conditions.

Catalyst-controlled site-selective N-H and C3-arylation of carbazole via carbene transfer reactions

A site-selective direct arylation reaction of carbazole and other N-heterocycles with diazo-naphthalen-2(1H)-ones has been developed. While Au(i)-NHC catalysts lead to selective C3-arylation, palladium acetate allows for selective N-H arylation, displaying complete site-selectivity each. To show the applicability of these arylation reactions, one-pot, two-fold diarylation reactions of carbazole were demonstrated.

Ir(iii)-Catalyzed direct C–H functionalization of N-phenylacetamide with α-diazo quinones: a novel strategy for producing 2-hydroxy-2′-amino-1,2′-biaryl scaffolds

A novel strategy is reported for the construction of 2-hydroxy-2′-amino-1,1′-biaryl scaffolds via Ir(iii)-catalyzed direct C–H bond activation under mild reaction conditions.

Rh(iii)-Catalyzed straightforward arylation of 8-methyl/formylquinolines using diazo compounds

A straightforward Rh(iii)-catalyzed general strategy was developed for the introduction of naphthol/phenol moieties to 8-methyl and formylquinolines using diazonaphthalen-2(1H)-ones/quinone diazides.

RhIII -Catalyzed Direct C8-Arylation of Quinoline N-Oxides using Diazonaphthalen-2(1H)-ones: A Practical Approach towards 8-aza BINOL

An efficient Rh^III -catalyzed redox-neutral method for the direct C8-arylation of quinoline N-oxides using diazonaphthalen-2(1H)-one as coupling partner has been demonstrated. The developed method is simple, scalable and straightforward with a wide range of substrate scope. The applicative potential was extended with a late-stage functionalization and straightforward synthesis of 8-azaBINOL derivative. A plausible reaction pathway was proposed after carrying out preliminary control studies.