Radical Reactions under Catalyst-Control: Titanium(III)-Catalyzed Reductive Umpolung Processes

The development of chemo-, regio- and stereoselective radical reactions has been a longstanding challenge in synthetic methodology. For catalytic radical reactions a high catalyst-control is required to achieve high selectivity and it is our goal to develop such catalyst-controlled radical reactions. In this lecture, titanium(III)-catalysis will be introduced as an excellent tool for selective radical couplings with the focus on so-called “reductive umpolung reactions”. These transformations enable the convenient synthesis of 1,2-, 1,4-, or 1,6-difunctionalized building blocks and lead to conceptually novel ways of constructing C-C bonds that are complementary to classical cross-coupling reactions. An overview of our methodology and its application in synthesis will be presented together with recent findings that give insight into the mechanism of these unique reactions.