Stereocontrolled Synthesis of Benzo[k]fluoranthenes-An Unexpected Isomerization Mediated by Rhodacyclopentadiene

Dienylation of Unfunctionalized Arenes with 1,6-Diynes via Rhodium-Catalyzed Directing-Group-Free C–H Bond Activation

It has been established that the dienylation of unfunctionalized arenes with 1,6-diynes, possessing aryl groups at the diyne termini, proceeds to give the corresponding dienylated arenes in the presence of a catalytic amount of an electron-deficient cyclopentadienyl rhodium(III) complex, [CpERhCl2]2, and a stoichiometric amount of silver carbonate. Experimental and theoretical mechanistic studies revealed that a CpERh(I) complex generated in situ might catalyze the present dienylation­ reaction.

Gold-Catalyzed Annulation of 1,8-Dialkynylnaphthalenes: Synthesis and Photoelectric Properties of Indenophenalene-Based Derivatives

A simple gold-catalyzed annulation of 1,8-dialkynylnaphthalenes utilizing a cationic gold catalyst was developed. Such a peri-position of two alkynyl substituents has not been studied in gold catalysis before. Dependent on the substrate, the reactions either follow a mechanism involving vinyl cation intermediates or involve a dual gold catalysis mechanism which in an initial 6-endo-dig-cyclization generates gold(I) vinylidene intermediates that are able to insert into C-H bonds. Indenophenalene derivatives were obtained in moderate to high yields. In addition, the bidirectional gold-catalyzed annulation of tetraynes provided even larger conjugated π-systems. The optoelectronic properties of the products were also investigated.

Rhodium-catalyzed cycloisomerization of ester-tethered 1,6-diynes with cyclopropanol moiety leading to tetralone/exocyclic diene hybrid molecules

The rhodium-catalyzed cycloisomerization of ester-tethered 1,6-diynes bearing a cyclopropanol moiety produced tetralone/exocyclic diene hybrid molecules with thermodynamically unfavorable alkene geometry. The results of control experiments and density functional theory calculations suggest that the ester tether plays an important role in the efficiency of E/Z isomerization processes.

Rhodium-Catalyzed [2+1+2+1] Cycloaddition of Benzoic Acids with Diynes through Decarboxylation and C≡C Triple Bond Cleavage

It has been established that an electron-deficient cyclopentadienyl rhodium(III) (Cp^E Rh^III ) complex catalyzes the oxidative and decarboxylative [2+1+2+1] cycloaddition of benzoic acids with diynes through C≡C triple bond cleavage, leading to fused naphthalenes. This cyclotrimerization is initiated by directed ortho C-H bond cleavage of a benzoic acid, and the subsequent regioselective alkyne insertion and decarboxylation produce a five-membered rhodacycle. The electron-deficient nature of the Cp^E Rh^III complex promotes reductive elimination giving a cyclobutadiene-rhodium(I) complex rather than the second intermolecular alkyne insertion. The oxidative addition of the thus generated cyclobutadiene to rhodium(I) (formal C≡C triple bond cleavage) followed by the second intramolecular alkyne insertion and reductive elimination give the corresponding [2+1+2+1] cycloaddition product. The synthetic utility of the present [2+1+2+1] cycloaddition was demonstrated in the facile synthesis of a donor-acceptor [5]helicene and a hemi-hexabenzocoronene by a combination with the chemoselective Scholl reaction.

Three-Step Synthesis of Fluoranthenes through Pd-Catalyzed Inter- and Intramolecular C-H Arylation

A three-step synthetic method for the preparation of fluoranthenes, involving Miura's intermolecular C-H arylation, nonaflation, and intramolecular C-H arylation, has been developed. Various 1-naphthols and haloarenes were successfully used as substrates. Reaction conditions that afford high site selectivity have been developed for the intramolecular C-H arylation step.

Rhodium(iii)-catalyzed oxidative bicyclization of 4-arylbut-3-yn-1-amines with internal alkynes through C–H functionalization

A new Rh(iii)-catalyzed oxidative bicyclization through C–H functionalization is presented for the synthesis of benzo[g]indoles.