Jianhui Wang

Controlled Reversible Immobilization of Ru Carbene on Single-Walled Carbon Nanotubes: A New Strategy for Green Catalytic Systems Based on a Solvent Effect on π−π Interaction

A pyrene-tagged ruthenium carbene 8 was synthesized and immobilized on single-walled carbon nanotubes (SWNTs) via pi-pi stacking. These pi-pi interactions were greatly affected by the reaction temperature and the solvent polarity, thus, offering a new reversible immobilization model that can be controlled by reaction temperature in polar solvents, such as acetone. SWNTs-supported ruthenium carbene 8 is a robust and recyclable catalyst system. Six to seven cycles were achieved for ring-closing metathesis of selected substrates. Importantly, after the complete loss of activity, the SWNTs can be easily recycled by washing with tetrahydrofuran. The recycled SWNTs can then be reloaded with 8. The reusability of the catalyst supported on recycled SWNTs is comparable with that supported on fresh SWNTs.

Rhodium-catalyzed decarbonylative cycloadditions of 1H-indene-1,2,3-triones and alkynes via direct C–C bond activation: divergent synthesis of indenones and quinones

A one-step preparation method for indenone and quinone derivatives via rhodium-mediated [5 + 2 − 2] and [5 + 2 − 1] decarbonylative cycloadditions of 1H-indene-1,2,3-triones and alkynes has been achieved. A rhodium(I) complex, [Rh(COD)Cl]2, with a bisphosphine rac-BINAP ligand was the most efficient catalytic system for this decarbonylative cycloaddition transformation. The [5 + 2 − 2] and [5 + 2 − 1] transformation processes can be enhanced by respectively adding copper chloride or hexacarbonyl chromium as an additive. This reaction is suitable for a broad range of alkynes and 1H-indene-1,2,3-triones and a variety of fused indenone and quinone derivatives were obtained in medium to high yields. More importantly, this work provides a new model for the direct activation of C–C bonds in less strained ketones without auxiliary groups.