Transition-metal-centered radicals in organic synthesis. Titanium(III)-induced cyclization of epoxy olefins

A Catalytic Enantioselective Electron Transfer Reaction: Titanocene-Catalyzed Enantioselective Formation of Radicals frommeso-Epoxides

“…5:2.5; 9: 60:40 vs. 81:19; 10: 70:30 vs. 87:13) or with stoichiometric amounts of reagent. [10] In summary we have demonstrated for the first time that the catalytic opening of meso-epoxides by electron transfer can be performed with high enantioselectivity and high diastereoselectivity with 1 as rationally designed catalyst. Received: April 23, 1999 [Z 13306 IE] German version: Angew.…”

Intramolecular Homolytic Substitutions in Synthesis

“…Ring opening of the epoxide results in the formation of an oxygen-metal bond. [53][54][55][56] Gansäuer and Grimme et al . were able to further develop this methodology to tandem radical chemistry that included a step in which the radical underwent homolytic substitution at oxygen, as depicted in Scheme 27.…”

A novel reduction of diketones with i-RMgBr catalyzed by Cp2TiCl2 and deoxygenation of sulfoxides by Cp2TiCl2/Al system

“…We recently found that Cp 2 TiCl 2 can be reduced by samarium to form a low-valent cyclopentadienyl titanium complex, which is a very effective reducing reagent (Yu and Zhang, 1995;Nugent and Rajanbabu, 1988). In order to extend the scope of application of the low-valent cyclopentadienyl titanium complex, we report that the Cp 2 TiCl 2 /Al system can be used as a deoxygenation reagent for reducing sulfoxides to sulfides under neutral and mild conditions (Fig.5).…”