*3.2. Synthesis of N-Tosyl Regioisomers 11 and 12*

A solution of *N*-tosyl-1*H*-indole-4,7-dione (500 mg, 1.66 mmol) in MeCN (80 mL) was treated with a solution of 2-aminoethanesulfinic acid (236 mg, 2.16 mmol) in H2O (50 mL) in one portion. The mixture was stirred for 20 h open to the atmosphere and then H2O was removed by rotary evaporation and the resulting solid collected by vacuum filtration. The crystals were washed with H2O (20 mL) then dried to afford a crude ~1:11 mixture of regioisomers **12** and **11**, respectively. This material (236 mg) was pre-adsorbed to C18-bonded silica (1 g) overnight, then packed into a guard cartridge that was subsequently attached to a C18-bonded silica semi-preparative HPLC column. Isocratic HPLC conditions of 90% H2O (0.1% TFA)/10% MeOH (0.1% TFA) were employed for the first 10 min, then a linear gradient to MeOH (0.1% TFA) was run over 40 min, followed by isocratic conditions of MeOH (0.1% TFA) for a further 10 min, all at a flow rate of 9 mL/min. Sixty fractions (60 × 1 min) were collected by time from the start of the HPLC run. All UV active fractions were analyzed by 1H-NMR spectroscopy and MS, and identical fractions were combined. This afforded **12** (7.6 mg, 1%, <sup>t</sup> R = 37.0–38.0 min) and **11** (69 mg, 10%, <sup>t</sup> R = 53.0–60.0 min). X-ray quality crystals of **11** were obtained through slow evaporation using a H2O/MeOH (1:9) mix.

Compound **11**: Dull orange crystals (H2O/MeOH); mp > 300 ◦C; 1H-NMR (600 MHz, DMSO-*d*6) δ<sup>H</sup> 2.42 (3H, s, H-15), 3.27–3.29 (2H, m, H-2), 3.76–3.78 (2H, m, H-3), 6.83 (1H, d, *J* = 3.4 Hz, H-6), 7.50 (2H, d, *J* = 8.2 Hz, H-13), 7.90 (2H, d, *J* = 3.4 Hz, H-7), 8.01 (2H, d, *J* = 8.2 Hz, H-12), 9.01 (1H, br s, H-4); 13C-NMR (150 MHz, DMSO-*d*6) δ<sup>C</sup> 21.2 (C-15), 39.3 (C-3), 48.2 (C-2), 107.5 (C-6), 108.2 (C-9a), 126.7 (C-5a), 128.6 (2C, C-12), 129.3 (C-7), 129.8 (2C, C-13), 130.8 (C-8a), 133.5 (C-11), 146.2 (C-14), 146.6 (C-4a), 167.1 (C-9), 175.1 (C-5); (+)-LRESIMS *<sup>m</sup>*/*<sup>z</sup>* (rel. int.) 407 (100) [M + H]+; (−)-LRESIMS *<sup>m</sup>*/*<sup>z</sup>* (rel. int.) 405 (100) [M − H]−; (+)-HRESIMS *<sup>m</sup>*/*<sup>z</sup>* 429.0200 [M + Na]<sup>+</sup> (calcd for C17H14N2NaO6S2, 429.0185).

Compound **12**: Bright orange amorphous solid; 1H-NMR (600 MHz, DMSO-*d*6) δ<sup>H</sup> 2.41 (3H, s, H-15), 3.26–3.28 (2H, m, H-2), 3.75–3.77 (2H, m, H-3), 6.81 (1H, d, *J* = 3.2 Hz, H-8), 7.48 (2H, d, *J* = 8.4 Hz, H-13), 7.98 (2H, d, *J* = 8.4 Hz, H-12), 8.12 (2H, d, *J* = 3.2 Hz, H-7), 9.13 (1H, br s, H-4); 13C-NMR (150 MHz, DMSO-*d*6) δ<sup>C</sup> 21.1 (C-15), 39.2 (C-3), 47.9 (C-2), 108.0 (C-9a), 108.8 (C-8), 125.9 (C-8a), 128.3 (2C, C-12), 130.0 (2C, C-13), 133.1 (C-11), 133.2 (C-7), 133.3 (C-5a), 146.4 (C-14), 147.4 (C-4a), 166.3 (C-5), 172.9 (C-9); (−)-LRESIMS *m*/*z* (rel. int.) 405 (100) [M − H]−; (+)-LRESIMS *m*/*z* (rel. int.) 407 (100) [M + H]+; (+)-HRESIMS *m*/*z* 429.0167 [M + Na]<sup>+</sup> (calcd for C17H14N2NaO6S2, 429.0185).
