Inner-Sphere Oxygen Activation Promoting Outer-Sphere Nucleophilic Attack on Olefins

摘要: Alkoxylation and hydroxylation reactions of 1,5-cyclooctadiene (cod) in an iridium complex with alcohols water promoted by the reduction oxygen to hydrogen peroxide are described. The exo configuration OH/OR groups products agrees nucleophilic attack at external face olefin as key step. also require presence a coordinating protic acid (such picolinic (Hpic)) involve participation cationic diolefin iridium(III) complex, [Ir(cod)(pic)2 ]+ , which has been isolated. Independently, this cation is involved easy alkoxy group exchange reactions, very unusual for organic ethers. DFT studies on mechanism alkoxylation mediated show low-energy proton-coupled electron-transfer step connecting superoxide-iridium(II) hydroperoxide-iridium(III) intermediates, rather than complexes. Accordingly, more reaction, up four different products, occurred upon reacting diolefin-peroxide Hpic. Moreover, such hydroperoxide intermediates origin regio- stereoselectivity hydroxylation/alkoxylation reactions. If protocol applied diolefin-rhodium(I) [Rh(pic)(cod)], free alkyl ethers ORC8 H11 (R=Me, Et) resulted, reaction enantioselective if chiral amino acid, l-proline, used instead