Malonic acid

Sodium arsenite, sodium arsenate dibasic heptahydrate (≥98%), methanol (Optima^TM for HPLC), tert-butanol (t-BuOH), acetonitrile (HPLC grade), o-phosphoric acid (85%, ACS grade), formic acid (88%), ammonium hydroxide (29.2%), and ferric chloride hexahydrate (FeCl₃·6H₂O, 98.8%) were purchased from Fisher Scientific (Waltham, MA, USA). Ferrous chloride tetrahydrate (FeCl₂·4H₂O, ≥99%), humic acid sodium salt (Lot#STBC5468V), coumarin (COU) (≥99%), potassium sorbate (≥99%), and 7-hydroxycoumarin (7-HC) (99%) were obtained from Sigma Aldrich (St. Louis, MO, USA). Furfuryl alcohol (FFA) and the tetrabutylammonium hydroxide (TBAH) (40 wt.%) were purchased from Acros Organic (Geel, Antwerp, Belgium). The 2,4,6-trimethylphenol (98%), was obtained from TCI (Portland, OR, USA). The malonic acid (reagent grade, 99.5%) was purchased from Alfa Aesar (Haverhill, MA, USA). Millipore water (MilliQ water, resistivity~18.0 MΩ cm⁻¹ at 25 °C) was used for sample and standard preparation unless otherwise indicated.

Coniferyl alcohol (Fig 1B) and Horseradish peroxidase (type II, 150–250 units/mg) were purchased from Sigma. Alexa 594-azide (Fig 1B), Murashige and Skoog salts, Shandon Cryomatrix resin, and monohydrate (2-(N-Morpholino)ethanesulfonic acid) (MES) were purchased from Life Technologies, Caisson Labs, Thermo Scientific, and Research Organics, respectively. All commercial materials for the chemical synthesis of 3-EPC were used as received unless otherwise noted. Flash chromatography was performed using 230–400 mesh SilicaFlash 60 silica gel (Silicycle Inc.). p-hydroxybenzaldehyde (99%, Acros), iodine monochloride (1 M solution in dichloromethane, Aldrich), malonic acid (99%, Alfa Aesar), trimethylsilyl acetylene (98%, Matrix Scientific), Bis(triphenylphosphine)palladium(II) chloride (99%, Aldrich), Diisobutylaluminium hydride (1 M solution in hexane, Acros), and tetrabutylammonium fluoride (1 M solution in tetrahydrofuran, Acros) were used for the chemical synthesis of 3-EPC. Other commercial chemicals, including solvents, were of reagent grade, purchased from Sigma-Aldrich, and used without further purification.