3.1. Synthesis of Compounds 2g and 2l

CS₂ (2.0 mmol) was added to a solution of amine (1) (4 mmol) in DMF (4 mL) in an ice-water bath. The mixture was stirred for 5 min. CBr₄ (2 mmol) was then added and the mixture was stirred at RT for a further 30 min. The mixture was poured into ice-water (40 mL) with stirring, and was then extracted with 2 × 40 mL CH₂Cl₂. The organic layer was dried over MgSO₄, concentrated under vacuum, and purified by column chromatography on silica gel to give the desired product.

Bis(N-ethoxycarbonylethylethylthiocarbamoyl)disulphide (2g): Column chromatography Silica Gel, CH₂Cl₂-MeOH (100/0 % to 98/2 %). Yield: 34% (viscous oil). IR: 2978, 2934, 1726, 1487, 1415, 1373, 1279, 1180, 1163 cm⁻¹. ¹H-NMR (400 MHz, CDCl₃): 1.27 (3H, bs), 1.48 (3H, bs), 2.86 (2H, bs), 3.01 (2H, bs), 4.05–4.30 (12H, bs). ¹³C-NMR (100 MHz, CDCl₃): 11.46, 13.50, 14.26, 14.33, 31.29, 33.03, 47.94, 49.18, 52.55, 52.85, 60.94, 61.23, 170.73, 171.72, 193.19, 193.51. HR-MS (ESI⁺) m/z [M + 1] calculated: 441.1010, found: 441.1015. The spectra are attached in the online Supplementary Material.

Bis(N-4-ethoxycarbonylbenzylethylthiocarbamoyl)disulphide (2l): Column chromatography Silica Gel, CH₂Cl₂ (100%). Yield: 23% (viscous oil). IR: 3059, 2976, 1710, 1610, 1481, 1458, 1408 cm⁻¹. ¹H NMR (400 MHz, CDCl₃): 1.20–1.50 (12H, m), 4.02 (4H, bs), 4.37 (4H, q, 3J = 7.2 Hz), 5.20–5.50 (4H, m), 7.30–7.55 (4H, m), 7.95–8.15 (4H, m). ¹³C-NMR (100 MHz, CDCl₃): 11.13, 11.31, 13.44, 14.43, 47.82, 52.53, 55.58, 59.47, 61.13, 127.54, 130.15, 139.64, 140.28, 193.94, 195.63. HR-MS (ESI⁺) m/z [M + 1] calculated: 565.1323, found: 565.1321. The spectra are attached in the online Supplementary Material.