Fig. 2: Reaction development.
From: Electrochemical cobalt-catalyzed semi-deuteration of alkynes to access deuterated Z-alkenes
a Optimization of reaction conditions. b Isotope labeling experiments. c Comparison of deuterium sources. d Cyclic voltammetry experiments. (i) Comparison of cyclic voltammograms obtained from different ratios of cobalt salts and ligands. (ii) Cyclic voltammogram of cathode reaction system. e Reaction kinetic experiments. (iii) Different-excess experiments under 2.5 mA current. (iv) Different-excess experiments under 7.5 mA current. (v) Burés graphical rate analysis for cobalt-salt and ligand complex under 7.5 mA current. Standard conditions: 1 (1.0 equiv., 0.050 mol/L), CoBr2 (5 mol%, 0.0025 mol/L), dtbpy (10 mol%, 0.005 mol/L), AcOD (5.0 equiv., 0.250 mol/L), PPh3 (4.0 equiv., 0.200 mol/L), TBABF4 (1.0 equiv., 0.050 mol/L), C(+)/C(-), 2.5 mA, 6.0 F/mol, DMAc (3.6 mL), D2O (0.40 mL), 500 rpm, 25 °C, under air. 0.2 mmol scales. GC (gas chromatography) yield. Deuterium content was determined by 1H-NMR (nuclear magnetic resonance) spectroscopy after isolation. ¶Isolated yields are given in parentheses. Co(OAc)2 cobalt acetate; Co(acac)2 bis(acetylacetonato)cobalt; DMAc N,N-dimethylacetamide, DMF N,N-dimethylformamide, DMSO dimethyl sulfoxide, TBABF4 tetrabutylammonium tetrafluoroborate, TBAI tetrabutylammonium iodide, TBAB tetrabutylammonium bromide, TEOA triethanolamine, DIPEA N,N-diisopropylethylamine, DABCO triethylenediamine, tBu tert-butyl, rpm revolutions per minute, nd not determined, D content was not detected when the GC yield was <30%, AcOH acetic acid, S22, hex-1-yn-1-ylbenzene.
