Visible light photoredox-catalyzed deoxygenation of alcohols

Abstract

SummaryCarbon–oxygen single bonds are ubiquitous in natural products whereas efficient methods for their reductive defunctionalization are rare. In this work an environmentally benign protocol for the activation of carbon–oxygen single bonds of alcohols towards a reductive bond cleavage under visible light photocatalysis was developed. Alcohols were activated as 3,5-bis(trifluoromethyl)-substituted benzoates and irradiation with blue light in the presence of [Ir(ppy)2(dtb-bpy)](PF6) as visible light photocatalyst and Hünig’s base as sacrificial electron donor in an acetonitrile/water mixture generally gave good to excellent yields of the desired defunctionalized compounds. Functional group tolerance is high but the protocol developed is limited to benzylic, α-carbonyl, and α-cyanoalcohols; with other alcohols a slow partial C–F bond reduction in the 3,5-bis(trifluoromethyl)benzoate moiety occurs.

Organic reactions for the electrochemical and photochemical production of chemical fuels from CO2 – The reduction chemistry of carboxylic acids and derivatives as bent CO2 surrogates

“…In recent reports, a photoredox variant has been reported [125]. In a similar vein, the Cu-catalyzed reduction of alkyl triflates to the corresponding alkane, has also been made available [126].…”

Synthesis of a polyisobutylene-tagged fac-Ir(ppy)3 complex and its application as recyclable visible-light photocatalyst in a continuous flow process

“…After cooling, the former two phases reappear, making the process fully reversible. 27 Substrate and reagents dissolved in heptane-saturated acetonitrile 28 (1) are pumped (2) into a microreactor (3) along with a solution of Ir(ppy) 2 (PIB--ppy) (3) in heptane (4). 22 Thus, for the photochemical reactions investigated, substrates and reagents were dissolved in acetonitrile at room temperature and catalyst 3 containing heptane was added (Scheme 2, (1)), forming a biphasic solution.…”

Enantioselective Visible‐Light‐Induced Radical‐Addition Reactions to 3‐Alkylidene Indolin‐2‐ones

“…Given the fact that 3‐alkylidene indolin‐2‐ones absorb at long wavelength, it was required to suppress this process. Initially, an irradiation wavelength of λ =457 nm was considered to be sufficient . The reactions progressed smoothly at ambient temperature (entry 1) and went also to completion at −25 °C ( c =10 m m ) in the presence of the template, but the enantiomeric excess ( ee ) was low (entry 2).…”