Sodium Hydroxide → 5-Methyl-6-oxoheptanesulfonic acid

Participants

Reaction Conditions

Reaction Steps

A solution of 290 mg of NaOH in 3 ml water was added to the mixture of 710 mg (2.53 mmol) of 5-ethyloxycarbonyl-5-methyl-6-oxo-1-heptanesulfonic acid in 15 ml of methanol. The obtained mixture was stirred for 15 hours at 50° C. Methanol was removed by a rotary evaporator, residue was acidified to pH 1 and then solvent was removed until dry to yield 5-methyl-6-oxo-1-heptanesulfonic acid. The product thus obtained (940 mg, 4.5 mmol), 1.02 g (5.4 mmol) of 4-hydrazinobenzenesulfonic acid, and 15 ml of acetic acid was refluxing for 16 hours. The insoluble precipitate was filtered and the filtrate was evaporated. The obtained residue was column purified (RP-18, water) to yield 840 mg of the 2,3-dimethyl-3-(4-sulfobutyl)-3H-5-indolesulfonic acid (IVd). δH (200 MHz, DMSO-d6): 7.66 (1H, s, arom H), 7.6 (1H, d, 8.0 Hz, arom H), 7.4 (1H, d, 7.8 Hz arom H), 2.66 (2H, t, 6.8 Hz, CH2SO3H), 2.32 (3H, s, 2-CH3), 2.10-1.78 (2H, m, CH2), 1.53-1.26 (2H, m, C H2), 1.31 (3H, s, 3-C H3), 0.83-0.41 (2H, m, CH2).

Provenance & Evidence