A Novel Catalysis of [{IrCl(cod)}2] Complex in Organic Syntheses

We have found that the [{IrCl(cod)}2] complex catalyzes several reactions involving three-component couplings, hydrogen migration, vinyl ethers synthesis, and α-alkylation of ketones with alcohols, etc. Thus, the reaction of aldehydes, amines, and alkynes under the influence of a catalytic amount of [{IrCl(cod)}2] complex led to three-component coupling products through a new type of C–H bond activation adjacent to the nitrogen atom of imines. Aziridines were also synthesized by three-component couplings of aldehydes, amines, and ethyl diazoacetate in the presence of a catalytic amount of [{IrCl(cod)}2]. An innovation in the synthesis of vinyl ethers, which are very useful monomer materials in polymer syntheses but have been difficult to synthesize so far, was made by a simple exchange reaction of alcohols with vinyl acetates through a catalytic process using [{IrCl(cod)}2]. A unique α-alkylation of ketones with alcohols was successfully achieved under the influence of [{IrCl(cod)}2] and KOH without any solvents, leading to saturated ketones that elongated the carbon chain. Allyl homoallyl and diallyl ethers were converted by [{IrCl(cod)}2] into γ,δ-unsaturated aldehydes via a Claisen rearrangement of in situ-generated allyl vinyl ethers. These reactions provide a novel synthetic tool for important chemicals like vinyl ethers and ketones, which are practically synthesized in the chemical industry.