4-Hydrazinobenzenesulfonic acid → 6-(2,3-dimethyl-5-sulfo-3H-indol-3-yl)hexanoic acid

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Reaction Steps

4-Hydrazinobenzenesulfonic acid (1.88 g, 10 mmol), 7-methyl-8-oxononanoic acid (2.8 g, 15 mmol) and glacial acetic acid (10 ml) were mixed and heated under reflux for 6 hrs. The solvent was then evaporated under vacuum and the residue triturated with diethyl ether until a solid was obtained. This was dried under vacuum to give crude product, 3.4 g (100%). This was purified by preparative HPLC as required (RPC18. Water+0.1% TFA→MeCN+0.1% TFA gradient). UV/Vis (Water+0.1% TFA): 274, 229, 204 nm. 1H-nmr (D2O) δ 0.6-0.9 (2H, broad m), 1.10-1.25 (2H, broad m), 1.35-1.50 (2H, m), 1.60 (3H, s), 2.10-2.40 (2H, broad m+2H, t), 7.77 (1H, d), 7.97 (1H, dd) and 8.06 (1H, d) MS (MALDI-TOF) MH+340.

Provenance & Evidence