Described here is atitanocene-catalyzed reaction for the synthesis of acetals and hemiaminals from benzylic ethers and benzylic amines,r espectively,with pendant epoxides.T he reaction proceeds by catalysis in single-electron steps.T he oxidative addition comprises an epoxide opening.AnH-atom transfer,t og enerate ab enzylic radical, serves as ar adical translocation step,a nd an organometallic oxygen rebound as ar eductive elimination. The reaction mechanism was studied by high-level dispersion corrected hybrid functional DFT with implicit solvation. The low-energy conformational space was searched by the efficient CREST program. The stereoselectivity was deduced from the lowest lying benzylic radical structures and their conformations are controlled by hyperconjugative interactions and steric interactions between the titanocene catalyst and the aryl groups of the substrate.A ni nteresting mechanistic aspect is that the oxidation of the benzylic center occurs under reducing conditions. Scheme 1. Atom-economic transformation of benzylic ethers into acetals by titanocene(III) catalysis in single-electrons teps (SET).

Described here is atitanocene-catalyzed reaction for the synthesis of acetals and hemiaminals from benzylic ethers and benzylic amines,r espectively,with pendant epoxides.T he reaction proceeds by catalysis in single-electron steps.T he oxidative addition comprises an epoxide opening.AnH-atom transfer,t og enerate ab enzylic radical, serves as ar adical translocation step,a nd an organometallic oxygen rebound as ar eductive elimination. The reaction mechanism was studied by high-level dispersion corrected hybrid functional DFT with implicit solvation. The low-energy conformational space was searched by the efficient CREST program. The stereoselectivity was deduced from the lowest lying benzylic radical structures and their conformations are controlled by hyperconjugative interactions and steric interactions between the titanocene catalyst and the aryl groups of the substrate.A ni nteresting mechanistic aspect is that the oxidation of the benzylic center occurs under reducing conditions. Scheme 1. Atom-economic transformation of benzylic ethers into acetals by titanocene(III) catalysis in single-electrons teps (SET).