N-(6-(5-amino-6-methylpyridin-3-yl)benzo[d]thiazol-2-yl)acetamide (101.9 mg, 0.342 mmol) and 4-dimethylaminopyridine (4.2 mg, 0.034 mmol) were suspended in pyridine (2.0 ml) and THF (2.0 ml) and benzenesulfonyl chloride (0.21 ml, 1.637 mmol) was added. The reaction was stirred under nitrogen at room temperature. After 1 day, more DMAP (21.3 mg) was added and stirring was continued. After about 2 hours, more benzenesulfonyl chloride (0.18 ml) was added, and stirring was continued. After 3.5 hours, flask put in preheated oil bath (65° C.) and stirring continued. After 45 minutes, LCMS shows mostly product, so reaction cooled to room temperature, concentrated and purified on a silica gel column (20:1 to 10:1 DCM/MeOH to 10:1 DCM/2 N ammonia in MeOH). Fractions with product collected, concentrated, treated with DCM, and filtered. Solid washed with DCM and Et2O, collected, and dried under high vacuum to afford N-(6-(6-methyl-5-(phenylsulfonamido)pyridin-3-yl)benzo[d]thiazol-2-yl)acetamide (38.0 mg, 25% yield). MS (ESI pos. ion) m/z: 439. Calculated exact mass for C21H18N4O3S2: 438.
