Recent Advances in Titanium Radical Redox Catalysis

Abstract

New catalytic strategies that leverage single-electron redox events have provided chemists with useful tools for solving synthetic problems. In this context, Ti offers opportunities that are complementary to late transition metals for reaction discovery. Following foundational work on epoxide reductive functionalization, recent methodological advances have significantly expanded the repertoire of Ti radical chemistry. This Synopsis summarizes recent developments in the burgeoning area of Ti radical catalysis with a focus on innovative catalytic strategies such as radical redox-relay and dual catalysis.

Shining Light on TiIV Complexes: Exceptional Tools for Metallaphotoredox Catalysis

“…Due to its intriguing redox properties, Ti-based organometallic chemistry was carefully described and fruitfully employed in the past decades for synthetically useful organic transformations. [22][23][24][25][26] Specifically, the Ti IV/III redox couple facilitates the access to radical intermediates with peculiar regio-and chemoselectivity otherwise not feasible by using other metal complexes. [27,28] Titanocenes (and mainly titanocene dichloride, Cp 2 Ti IV Cl 2 ) offer a wide range of possible applications.…”

Cp2TiIIICl Catalysis in a New Light

“…[13][14][15] With these inspiring works, Cp 2 Ti III Cl has become a powerful tool for the development of new, highly enabling synthetic methodologies in contemporary radical chemistry. [16][17][18][19][20][21] In general, this reagent has been generated via chemical reduction of Cp 2 TiCl 2 with stoichiometric reductive metals such as metallic manganese or zinc and can be obtained as a green crystalline powder. The structure of Cp 2 Ti III Cl in solution was studied and proposed to be the equilibrium of dinuclear 1 and mononuclear 2 species.…”

Photocatalytic Generation of π-Allyltitanium Complexes from Butadiene via a Radical Strategy

“…These features and its rich redox properties make titanium especially attractive for organic transformations. 21,22 Metallaphotoredox catalysis is a new and rapidly growing research subject. [23][24][25][26][27] In this backdrop, our group developed the first dual titanium and photoredox catalysis for the radical opening/cyclization of epoxides.…”