Electrochemical hydrogenation of a benzannulated pyridine to a dihydropyridine in acidic solution

Abstract

The electrochemistry of pyridines in acidic solution is dominated by a 'weak acid' reduction on the cyclic voltammetry timescale. Here we show that electrochemical hydrogenation of a benzannulated pyridine, phenanthridine (1), to the biomimetic hydride donor 1,2-dihydrophenanthridine (1-H2) can occur selectively at glassy carbon electrodes over longer timescales of potentiostatic electrolysis.

Catalytic C–H Bond Alkylation of Azoles with Alkyl Halides Mediated by Nickel(II) Complexes of Phenanthridine-Based N^N–^N Pincer Ligands

“…The solid-state structures of the phenanthridine-containing proligands 3a-c were determined using single crystal X-ray diffraction (Figure 2). Consistent with the general importance of 'imine-bridged biphenyl' resonance contributors to the ground-state structure of phenanthridines, 23 the C-N distance between the phenanthridinyl nitrogen and the adjacent carbon in the 6-position is quite short in all three proligands [3a: C(1)-N(1)…”

Electrochemical hydrogenation of α-ketoesters and benzoxazinones using carbon electrodes and a sustainable Brønsted acid

“…24,25 Similarly, the selective hydrogenation of benzannulated pyridines such as phenanthridine to form 1,2dihydrophenanthridine has also been observed when the equivalents of acid present are appropriately controlled. 26 To probe the generality of this process, we sought to investigate the electrochemical hydrogenation of two substrate classes, aketoesters and benzoxazinones (Figure 2), that have been previously explored in the context of biomimetic dihydrophenanthridine-mediated transfer hydrogenation. 27,28 First, cyclic voltammograms (CVs) of a-ketoester (1a-k) and benzoxazinone (2a-g) substrates were recorded using freshly polished glassy carbon disc electrodes (surface area = 7.068 mm 2 ) under neutral and acidic conditions.…”

Advances and challenges in modeling solvated reaction mechanisms for renewable fuels and chemicals

“…Experimentally validating these computational predictions has been difficult, in part due to difficulties reproducing experimental data that has been reported in the literature . However, other experimental studies have implicated transiently formed hydride‐containing species in CO 2 reduction that are intermediates predicted to be thermodynamically stable by Pourbaix diagram analyses . From our perspective, we see opportunities to use computational modeling to discover new catalysts in chemical and materials space and synergistically guide experimental design with high‐throughput screening.…”

“…42,43 However, other experimental studies have implicated transiently formed hydride-containing species in CO 2 reduction that are intermediates predicted to be thermodynamically stable by Pourbaix diagram analyses. 44,45 From our perspective, we see opportunities to use computational modeling to discover new catalysts in chemical and materials space and synergistically guide experimental design with high-throughput screening. However, though numerous hurdles pertaining to modeling reaction mechanism under solvating reaction conditions must be overcome first.…”