1,4-Dioxane → 5-(2-methoxyphenyl)-N-(1,2,4-thiadiazol-5-yl)naphthalene-2-sulfonamide

Participants

Reaction Conditions

Reaction Steps

A vial was charged with 5-bromo-N-(2,4-dimethoxybenzyl)-N-(1,2,4-thiadiazol-5-yl)naphthalene-2-sulfonamide (INTERMEDIATE D) (73.69 mg, 0.142 mmol), 2-methoxyphenylboronic acid (43.0 mg, 0.283 mmol), Pd(AmPhos)2Cl2 (5.01 mg, 7.08 μmol), potassium phosphate (90 mg, 0.425 mmol), 1,4-dioxane (708 μl), and water (236 μl). The vial was sealed and heated in a microwave reactor for 30 min at 100° C. The mixture was diluted with water and extracted with EtOAc (3×). The combined organic extracts were concentrated. The residue was dissolved in DCM (1 mL) and TFA (0.5 mL). After 2 h, the mixture was diluted with MeOH and filtered through diatomaceous earth with the aid of DCM. The filtrate was concentrated. The residue was purified twice by chromatography on silica gel (12-g columns, first with 0 to 5% MeOH/DCM, then with 2.5% MeOH/DCM), and the resulting material was dissolved in DCM and loaded onto a 1-g PE-AX ion exchange column (Biotage AB, Uppsala, Sweden). The column was flushed with 1:1 MeOH/DCM, then eluted with 10% HCl/MeOH (made by dissolving 1 mL on conc. HCl in 9 mL of MeOH). The acidic fraction was concentrated to give 5-(2-methoxyphenyl)-N-(1,2,4-thiadiazol-5-yl)naphthalene-2-sulfonamide (41.62 mg, 0.105 mmol, 74.0% yield) as an off-white solid: 1H NMR (400 MHz, DMSO-d6) δ ppm=8.59-8.44 (m, 2H), 8.20 (d, J=8.2 Hz, 1H), 7.77-7.66 (m, 2H), 7.58 (d, J=8.9 Hz, 1H), 7.54-7.45 (m, 2H), 7.26-7.16 (m, 2H), 7.13-7.05 (m, 1H), 3.63 (s, 3H); m/z (ESI) 398.2 (M+H)+.

Provenance & Evidence