Tert butyl acrylate t ba

Tert-butyl acrylate (t-BA) (Alfa Aesar, 99%) and n-butyl acrylate (n-BA) (Alfa Aesar, Ward Hill, MA, USA, 98%) were passed through the neutral Al₂O₃ (Fluka, Buchs, Switzerland) column to remove the inhibitor. Copper(I) bromide (Aldrich, San Diego, CA, USA, 98%), ethyl 2-bromopropionate (EBP) (Aldrich, 98%), N, N, N′, N″, N″-pentamethyldiethylenetriamine (PMDETA) (Acros, Geel, Belgium, 98%), butanone (Fisher Chemical, Hampton, NH, USA, 99%), isopropyl alcohol (Macron, Dunkirk, France), and 3,4,5-trimethoxybenzaldehyde, 98% (Alfa-Aesar) and 1,4-dioxane (Merck, Boston, MA, USA, 99%), HCl (Valerus, Sofia, Bulgaria, 36%), dimethylformamide (DMF) (Merck, 99.9%), methanol (Acros), tetrahydrofuran (THF) (Macron) were used as received.

The generation of GNA was obtained by extraction and isolation from the gamboge’s resin (98%). ε-Caprolactone (CL, 99%) was treated with distillation under reduced vacuum. Tert-butyl acrylate (tBA, 98%, Alfa Aesar) was purified through a basic alumina column. Stannous octoate (Sn (Oct) 2, 97%) was used as received. 2,2′-azobis (isobutyronitrile) (AIBN) was recrystallized twice from ethanol. Prop-2-ynyl-3-(5-cyano-5-phenylthiocarbonylsulfanyl) pentanoyloxy-2-(2,2-dihyd -roxymethyl)-propionyloxymethyl-2-methylpropanoate (PCBP) was prepared and purified in reference to literature procedures [30 (link)].