Carborane-arene fused boracyclic analogues of polycyclic aromatic hydrocarbons accessed by intramolecular borylation.

Arenes are 2D aromatics while dicarbadodecaborane clusters are branded as 3D aromatic molecules. In this work we prepare molecules that feature fused 2D/3D aromatic systems that represent boron-doped analogues of polycyclic aromatic hydrocarbons. The electron withdrawing nature of the ortho-carborane substituent enables swift arene borylation on boron bromide or hydride precursors to furnish five- and six-membered boracycles in conjugation with the arene. The mechanism was modeled by DFT computations implying a concerted transition state and analyzing the photophysical properties revealed high quantum yields in the six-membered systems.

Triple-Decker Iron and Cobalt Complexes Featuring a Bridging 1,2-Diboratabenzene Ligand.

Neutral triple-decker iron and cobalt complexes with a bridging 1,2-diboratabenzene ligand were accessed by reactions of a dilithium 1,2-diboratabenzene reagent with [Cp*FeCl]2 and [Cp*CoCl]2, respectively. While 1,2-diboratabenzene metal complexes are known, these represent the first examples of the ligand bridging two metals.

Assessing the donor ability of boratabenzene and 9-borataphenanthrene anions through metal complexes with carbonyl ligands.

A series of anionic group 6 tricarbonyl and neutral rhodium dicarbonyl complexes featuring a boratabenzene (L1, with a phenyl on boron, a trimethylsilyl group on the adjacent carbon and methyl groups on the other carbons) and a borataphenanthrene ligand (L2, with a phenyl group on boron and a trimethylsilyl group on the adjacent carbon) are prepared. The donor ability of the boracyclic ligands is evaluated experimentally and theoretically by the stretching frequencies of the CO ancillary ligands. Overall, the donor ability of the ligands falls into the following trend: L1 > cyclopentadienyl > L2 > mesitylene.

Rh(iii)-Catalysed synthesis of cinnolinium and fluoranthenium salts using C-H activation/annulation reactions: organelle specific mitochondrial staining applications.

The construction of a novel class of indazolo[2,1-a]cinnolin-7-ium and diazabenzofluoranthenium salts was developed by using Rh(iii)-catalyzed C-H activation/annulation reactions with 2-phenyl-2H-indazole, and internal alkynes, which resulted in structurally important polycyclic heteroaromatic compounds (PHAs). This reaction uses mild reaction conditions and has a high efficiency, low catalyst loading, and wide substrate scope. The overall catalytic process involves C-H activation followed by C-C/C-N bond formation. Furthermore, the synthesised cinnolinium/fluoranthenium salts exhibit potential fluorescence properties and 5i was targeted in particular for specific mitochondrial staining in order to investigate cancer cell lines.

Harnessing hypervalent iodonium ylides as carbene precursors: C-H activation of N-methoxybenzamides with a Rh(iii)-catalyst.

Hypervalent iodonium ylides expeditiously generate carbenes which undergo domino intermolecular C-H activation followed by intramolecular condensation in the presence of N-methoxybenzamide as a starting material and a Rh(iii)-catalyst to afford dihydrophenanthridines. KIE studies and DFT calculations were performed to substantiate the mechanistic pathway. To extend the synthetic utilisation, fluorescent pyranoisocoumarins were achieved by using Rh(iii)-catalyzed peri-C-H/O-H activation/annulation reactions.

Rhodium(III)-Catalyzed Redox-Neutral 1,1-Cyclization of N-Methoxy Benzamides with Maleimides via C-H/N-H/N-O Activation: Detailed Mechanistic Investigation.

An Rh(III)-catalyzed 1,1-cyclization of N-methoxy benzamides with maleimides providing isoindolinone spirosuccinimides through N-H/C-H/N-O bond activation is described. The detailed mechanistic investigation including isolation of key metalacycle intermediate, deuterium labeling studies, and DFT calculations were performed. The computational study reveals that the AcOH that formed in the reaction medium plays a key role in the N-OMe bond cleavage and the oxidation of Rh(I) to Rh(III).

Ruthenium(II)-Catalyzed Regioselective-Controlled Allenylation/Cyclization of Benzimides with Propargyl Alcohols.

A ruthenium(II)-catalyzed cyclization of benzimidates with substituted propargyl alcohols to provide 3,4-disubstituted 1-alkoxy isoquinolines in a highly selective manner via the C-H allenylation is described. The proposed reaction mechanism of the ruthenium(II)-catalyzed cyclization reaction is strongly supported by the isolation of the key ruthenacycle intermediate, deuterium-labeling studies, and detailed DFT calculations including the transition states.

Ruthenium(II)-Catalyzed Cyclization of Aromatic Acids with Allylic Acetates via Redox-Free Two-Fold Aromatic/Allylic C-H Activations: Combined Experimental and DFT Studies.

A Ru(II)-catalyzed, redox-free, two-fold aromatic/allylic C-H bond activation of aromatic acids with allylic acetates to give ( Z)-3-ylidenephthalides is described. In the reaction, H2 was formed as a side product. The detailed mechanistic investigation and DFT studies including the transition-state analysis support the postulate that the C-H allylation takes place at the ortho position of aromatic acids with allylic acetates followed by intramolecular cyclization at the allylic C(sp3)-H via a π-allylruthenium intermediate.

Ruthenium(II)-Catalyzed Redox-Free [3 + 2] Cycloaddition of N-Sulfonyl Aromatic Aldimines with Maleimides.

A ruthenium(II)-catalyzed redox-free cycloaddition of N-sulfonyl aromatic aldimines with maleimides providing 1-aminoindanes in good yields is described. Usually, maleimides reacted with substituted aromatics, affording the Michael-type ortho alkylated aromatics or 1,1-type cyclized spirosuccinimides. In the present reaction, maleimides provided 1,2-type cycloaddition products. The proposed mechanism was strongly supported by the DFT calculations and isolation of a ruthenacycle intermediate.

Ruthenium(II)-Catalyzed Redox-Neutral Oxidative Cyclization of Benzimidates with Alkenes with Hydrogen Evolution.

1H-Isoindoles and 2H-isoindoles are synthesized via a ruthenium-catalyzed oxidant-free cyclization of benzimidates with alkenes at room temperature with the liberation of H2. Later, 1H-isoindoles were converted into nitrogen-containing heterocycles. The proposed reaction mechanism was strongly supported by experimental evidence and DFT calculations.

A [Fe(CB6)] platform for binding of small molecules: insights from DFT calculations.

The viability of making [Fe(CB(6))L] (L = H(2), N(2), O(2), nitric oxide [NO(-), NO, and NO(+)], CO(2), and hydrocarbons [CH(4), C(2)H(6), C(2)H(4), and C(6)H(6)]) has been investigated by density functional theory (DFT) calculations. The complexes 2-18 are thermodynamically stable and may be synthesized. The small molecules are activated to some extent after complexation. Molecular orbital and ΔG calculation revealed that the molecular hydrogen and hydrocarbons can be chemically adsorbed and desorbed on [Fe(CB(6))] without any significant chemical modification and therefore [Fe(CB(6))] may serve as a storage material. The N(2), O(2), and nitric oxide (NO(-), NO, and NO(+)) can be activated using [Fe(CB(6))]. Proton, carbon, boron, and nitrogen NMR chemical shift calculation predicts drastic chemical shift difference before and after the complexation of [Fe(CB(6))] with small molecules. This new findings suggest that the CB(6)(2-) ligand-based complex may provide several applications in the future.