4-Hydrazinobenzenesulfonic acid → 2,3-Dimethyl-3-(4-sulfobutyl)-3H-indole-5-sulfonic acid

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Reaction Steps

4-Hydrazinobenzenesulfonic acid (1.88 g), 5-methyl-6-oxoheptanesulfonic acid (2.5 g) and acetic acid (50 ml) were mixed and heated under reflux for 6 hrs. The solvent was evaporated under vacuum, then the residue was triturated with 2-propanol to yield the crude product as a yellow solid. This was purified by HPLC as required (RPC18. Water+0.1% TFA). 1H-nmr (D2O) δ0.8-1.0 (2H, m), 1.55-1.65 (5H, =3H, s+2H, m), 2.16 (1H, ddd), 2.29 (1H, ddd), 2.75 (2H, m), 2.81 (partially d-exchanged methyl singlet), 7.71 (1H, d), 7.94 (1H, d) and 8.01 (1H, d). UV/Vis (Water+0.1% TFA): 269, 229 nm. MS (LCMS): MH+362. Acc. Mass: Found, 362.0729. MH+=C14H20NO6S2 requires 362.0732 (−0.8 ppm).

Provenance & Evidence