Abstract:The water-soluble iridium complex {Cp*Ir--pentamethylcyclopentadienyl, bpy = 2,2'-bipyridine) was found to be a general and highly efficient catalyst for the Nalkylation of the poor nucleophilic sulfonamides with alcohols as alkylating agents in water. The presence of OH units in the bpy ligand is crucially important for the catalytic activity of the iridium complex. Mechanistic investigations revealed that the catalytically active species is a ligand-metal bifunctional iridium complex bearing an N,N'-chelated 2,2'-bipyridinated ligand and an aqua ligand. Notably, the present catalytic system and the proposed mechanism provide a new horizon and scope for the development of "hydrogen autotransfer (or hydrogen-borrowing) processes".

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Red card for formaldehyde: The direct coupling of indoles with methanol to 3,3'-bisindolylmethanes with good to excellent yields was accomplished by using a commercially available iridium complex. This study demonstrates the potential of direct use of methanol as an alternative to formaldehyde for synthetic transformations.

In the same boat: Tandem rearrangement/N‐alkylation reactions in the presence of a Ru/Ir dual‐catalyst system affords the desired N‐alkylated amines in good‐to‐excellent yields with no intermediate amides or over‐alkylated N,N‐dialkylated amides. This environmentally friendly tandem reaction employs readily available starting materials, affords excellent selectivities for the N‐alkylated amides, and shows high atom efficiency.

R = aryl or aliphatic group phosphorous ligand-free low catalytic loading under air atmosphere up to 93% yield; 37 examples.