Silica gel column

Nonyl protocatechuate was prepared as previously described by Faria et al. [37 (link)], Soares et al. [30 (link)], and Costa-Orlandi et al. [7 (link)]. Briefly, the synthesis was performed by standard esterification reactions using protocatechuic acid (Sigma-Aldrich, St. Louis, MO, USA) and nonyl alcohol, in N′,N′-dicyclohexylcarbodiimide (DCC) and p-dioxane. The residue was partitioned with ethyl acetate and filtered. The filtrate was washed with NaHCO₃ solution and water and dried over MgSO₄. The crude product was purified over a silica gel column (0.06–0.02 mm, A.C.R.O.S. Organics, Waltham, MA, USA) and eluted using CHCl₃/CH₃OH (98:2). The structure of the compound was confirmed using ¹H and ¹³C Nuclear Magnetic Resonance spectroscopy. NMR spectra were recorded using a Bruker spectrometer (300 MHz, 7.1 T). The purity of the compound was determined by high-performance liquid chromatography with a photodiode array detector (HPLC-PAD) using the peak area. HPLC-PAD chromatograms were obtained on Agilent Technologies 1220 Infinity equipment, a photodiode array system (Agilent Technologies Model 1260 Infinity), and an Agilent Zorbaz Eclipse Plus C-18 column (250 mm × 4.6 mm, 5 µm) using methanol:water (98:2) as the mobile phase (1.0 mL/min). The NMR spectra and HPLC chromatograms are presented in the Supplementary Material (Figures S1–S3).

To a solution of 1.00 g (6.7 mmol) of triflamide and 0.51 g (6.7 mmol) of allyl chloride 1 in 30 mL of tetrahydrofuran was added 1.19 g (6.7 mmol) of NBS, and the reaction mixture was kept in the dark for 24 h. The solvent was removed under reduced pressure, the residue was dissolved in 20 mL of diethyl ether, mixture was cooled and succinimide was filtered off. The filtrate was evaporated in vacuo, the residue (~2.20 g) was placed on a silica gel column (0.063–0.2 mm, Acros Organics, Waltham, MA, USA) and eluted with ether:hexane = 1:1 mixture, isolating unreacted triflamide, then with ether, obtaining 0.30 g of 1,2- dibromo-3-chloropropane 16 as a yellow oil. Product 16 was obtained and described earlier [26 (link)].

To a solution of 1.00 g (6.7 mmol) of triflamide and 0.39 g (6.7 mmol) of allyl alcohol 4 in 25 mL of acetonitrile was added 1.19 g (6.7 mmol) of NBS, and the reaction mixture was kept in the dark for 24 h. The solvent was removed under reduced pressure, the residue was dissolved in 20 mL of diethyl ether, cooled and the formed succinimide was filtered off. The filtrate was evaporated in vacuum, the residue (1.79 g) was placed on a silica gel column (0.063–0.2 mm, Acros Organics, Waltham, MA, USA) and eluted with ether:hexane = 1:1 mixture, isolating unreacted triflamide (~0.4 g), then with ether, obtaining N-(2-bromo-3-hydroxypropyl)-N’-(trifluoromethylsulfonyl)acetamidamide 12 as a colorless oil.
N-(2-Bromo-3-hydroxypropyl)-N’-(trifluoromethylsulfonyl)acetamidamide, 12. Yield 0.34 g, 26%. The product was obtained earlier and described in [16 (link)].