Methyl iodide → Sodium

Participants

Reaction Conditions

Reaction Steps

N-Cbz-7-Aminonaphthalene-2-sulfonic acid, sodium salt is prepared as described in EXAMPLE 39, Part A using 7-aminonaphthalene-2-sulfonic acid, sodium salt (3 g, 12.2 mmol) in place of 6-aminonaphthalene-2-sulfonic acid, sodium salt. A 60% dispersion of sodium hydride (0.21 g, 5.27 mmol) in mineral oil is washed with hexanes twice, suspended in 20 mL of DMF and the resulting suspension is cooled to 0° C. To this mixture is added the crude N-Cbz-7-aminonaphthalene-2-sulfonic acid, sodium salt (1 g, 2.64 mmol) in 15 mL of DMF. The reaction mixture is stirred for 10 min at 0° C. and then treated with methyl iodide (0.49 mL, 7.92 mmol). The resulting mixture is allowed to warm to room temperature with stirring overnight. The reaction mixture is worked up according to the similar procedure used in EXAMPLE 32, Part A to yield the crude N-Cbz-7-methylaminonaphthalene-2-sulfonic acid, sodium salt (0.88 g) as a beige solid. A mixture of the sulfonic acid, sodium salt (0.88 g, 2.23 mmol) is chlorinated as described in EXAMPLE 32, Part A. The crude product is purified by column chromatography in a gradient of 10% EtOAc/hexanes to 30% EtOAc/hexanes to afford the title compound (0.38 g, 0.97 mmol) as a beige solid.

Provenance & Evidence