Gold‐Catalyzed Highly Selective Photoredox C(sp²)−H Difluoroalkylation and Perfluoroalkylation of Hydrazones

Abstract

The first gold-catalyzed photoredox C(sp(2) )-H difluoroalkylation and perfluoroalkylation of hydrazones with readily available RF -Br reagents is reported. The resulting gem-difluoromethylated and perfluoroalkylated hydrazones are highly functionalized, versatile molecules. A mild reduction of the coupling products can efficiently produce gem-difluoromethylated β-amino phosphonic acids and β-amino acid derivatives. In mechanistic studies, a difluoroalkyl radical intermediate was detected by an EPR spin-trapping experiment, indicating that a gold-catalyzed radical pathway is operating.

Synthesis, Solvatochromic Performance, pH Sensing, Dyeing Ability, and Antimicrobial Activity of Novel Hydrazone Dyestuffs

“…is arylhydrazone anion acts as an electron-donating moiety in conjugation with the strong electron-deficient tricyanofuran moiety leading to an interesting spectral switch of a donor-acceptor molecular system under pH stimulus [24]. Figure 3 displays the UVvisible absorption spectra and color changes of dye 1 dissolved in acetonitrile (ca.…”

“…Hydrazones are originally a Schiff-base group of materials possessing a secondary amine proton comprising an important category of compounds in a diversity of research fields, such as nonlinear optics, sensors, and a variety of biological and medical applications [16][17][18][19][20][21][22][23][24][25][26].…”

Reaction Pathway Dependence in Plasmonic Catalysis: Hydrogenation as a Model Molecular Transformation

“…One of the very first reports on catalytic activity of gold nanoparticles covered hydrogenation . Considering photochemical catalysis, the effect of light excitation has been investigated with mono‐ and dinuclear gold(I) complexes . Regarding plasmonic catalysis, the effect of light excitation on the H 2 and D 2 exchange over Au/TiO 2 and Au/SiO 2 catalysts has been reported .…”

“…[56,57] Considering photochemicalc atalysis, the effect of light excitation has been investigated with mono-and dinuclearg old(I) complexes. [58][59][60][61][62][63] Regarding plasmonicc atalysis, the effect of light excitation on the H 2 and D 2 exchange over Au/TiO 2 and Au/SiO 2 catalysts has been reported. [46,47] In these examples, it has been demonstrated that localized surface plasmon resonance-excited hot electrons are able to facilitatet he H 2(g) splitting rate at the surface of the nanoparticles at room temperature when these materi-als are excited by green light.…”

New Prospects toward the Synthesis of Difluoromethylated Phosphate Mimics

“…[25] Very recently, a new approach based on a gold-catalyzed C(sp 2 )-H phosphonyldifluoromethylation of hydrazone derivatives was reported by Hashmi and co-workers. [26] Taking benefit from the recent advances in photoredox catalysis, the astute combination of gold photocatalyst [Au(m-dppm) 2 ](OTf) 2 with UVA irradiation to form a phosphonodifluoromethylene radical, generated from BrCF 2 PO(OEt) 2 , furnished an efficient pathway toward the addition of such a phosphate mimic onto carbonyl derivatives. A large panel of hydrazine derivatives was efficiently functionalized with complete stereocontrol since only E isomers were synthesized.…”