Ruthenium-Catalyzed Annulation Research Articles

Ru(II)-Catalyzed Synthesis of Fused Imidazo[1,2-a]pyridine-chromenones and Methylene-Tethered Bis-imidazo[1,2-a]pyridines and Regioselective O-Acetoxylation of Imidazo[1,2-a]pyridines

Herein, we disclose an unprecedented protocol via ruthenium-catalyzed annulation for the synthesis of 6H-chromeno[4',3':4,5]imidazo[1,2-a]pyridin-6-one, and functionalized 2-(3-formylimidazo[1,2-a]pyridin-2-yl)phenyl acetate has been revealed by intramolecular chelation-assisted C-H activation. Additionally, a one-pot approach for creating bis(2-phenylimidazo[1,2-a]pyridin-3-yl)methane (BIP) has been realized through ruthenium catalysis with the use of formic acid. This method was used in gram-scale synthesis of BIP and step-economical late-stage functionalization of a marketed drug, zolimidine, in good yield.

Ruthenium(II)-catalyzed facile synthesis of 3-(phenylamino)-1H-indole-2-carboxylates from anilines and diazo pyruvates promoted by FeCl3

Abstract An unprecedented synthetic route towards a variety of 3-anilino-1H-indoles is accomplished from diazo pyruvates and anilines via a domino ruthenium-catalyzed annulation and subsequent iron promoted fragmentation and rearrangement. The current strategy was amenable to deliver diversely substituted indole esters, which were subjected to in vitro anti-cancer activity assessment using CCK-8 assay. Compound 4i displayed the best inhibition activity with IC50 value of 0.05 μM, triggering the initiation towards discovering promising lead compounds in the future.

Ruthenium-Catalyzed Annulation of N-Cbz Hydrazones via C–H/N–N Bond Activation for the Rapid Synthesis of Isoquinolines

In this work, N-Cbz hydrazone has been employed as a rarely explored directing group for the synthesis of isoquinolines by annulation with internal alkynes via C–H/N–N activation using Ru catalyst. Additive as well as external oxidant-free rapid protocol has been established for the synthesis of isoquinolines using microwave strategy. Use of non-volatile and biodegradable PEG as a green solvent with lower catalyst loading makes the proposed protocol environmentally benign. Further, higher functional group tolerance and wide substrate scope has been observed under the stated methodology with higher yields.

Ruthenium-catalyzed annulation of aromatic ketones with internal alkynes: A reliable route to substituted naphthalene derivatives

We report herein the preparation of polysubstituted naphthalene derivatives by the ruthenium-catalyzed benzannulation reaction of aromatic ketones with internal alkynes. This method (1) forms two new carbon-carbon bonds in one single step, (2) accommodates a variety of functional groups, and (3) undergoes mild reaction conditions.

ChemInform Abstract: Synthesis of Silaphenalenes by Ruthenium‐Catalyzed Annulation Between 1‐Naphthylsilanes and Internal Alkynes through C—H Bond Cleavage.

AbstractThe use of asymmetric alkynes affords mixtures of regioisomers.

Synthesis of Silaphenalenes by Ruthenium-Catalyzed Annulation between 1-Naphthylsilanes and Internal Alkynes through C-H Bond Cleavage.

Ruthenium-catalyzed annulation of 1-naphthylsilanes with internal alkynes afforded silaphenalenes through cleavage of the C-H bond at the 8-position of the naphthalene. [RuH2 (CO){P(p-FC6 H4 )3 }3 ] efficiently catalyzed the reaction. The use of 1-naphthyldiphenylsilane as a substrate resulted in a better yield of the annulation product compared to the use of silanes with alkyl groups on the silicon atom. Internal alkynes with both aryl and alkyl groups were tolerated in this reaction.

Ruthenium-catalyzed annulation of alkynes with amides via formyl translocation

The first example of Ru-catalyzed intramolecular annulation of alkynes with amides via formyl translocation has been developed, which provides an efficient approach for the synthesis of 1H-indole-3-carbaldehydes.