Reaction Steps
In a 5-mL conical microwave vial equipped with a stir bar, 2-((1-(3-bromobenzyl)-4,6-difluoro-1H-indol-3-yl)sulfonyl)-N-(pyridin-2-yl)acetamide (30 mg, 0.058 mmol, Example 7), sodium azide (10 mg, 0.15 mmol)), CuI (2.5 mg, 0.013 mmol), N,N′-dimethylaminediamine (2.0 mg, 0.23 mmol), and sodium ascorbate (5.0 mg, 0.025 mmol) were massed. The reagents were suspended in ethanol/water (2:1, 5 mL) and the vial was sealed with a crimped cap. The reaction was heated to 120° C. with microwave irradiation for 2 hours. The reaction was cooled to room temperature and diluted with ethyl acetate (20 mL) and brine (20 mL). The layers were separated, and the aqueous layer was extracted with ethyl acetate (2×20 mL). The combined organic layers were dried over MgSO4, filtered, and concentrated in vacuo. The crude residue was purified by flash column chromatography eluting with hexanes/ethyl acetate to afford the pure desired compound, 2-((1-(3-azidobenzyl)-4,6-difluoro-1H-indol-3-yl)sulfonyl)-N-(pyridin-2-yl)acetamide. Into a dry round bottom flask equipped with a stir bar and septum, 2-((1-(3-azidobenzyl)-4,6-difluoro-1H-indol-3-yl)sulfonyl)-N-(pyridin-2-yl)acetamide (12 mg, 0.025 mmol), trimethylsilyl acetylene (6.0 mg, 0.61 mmol), copper sulfate (2.0 mg, 0.012 mmol), and sodium ascorbate (4.0 mg, 0.020 mmol) were added. The flask was purged with argon, and the reagents dissolved in MeOH/H2O (2:1, 4 mL). The reaction was stirred at room temperature for 24 hours and monitored by LCMS. Upon completion, the reaction was diluted into dichloromethane (20 mL) and brine (20 mL). The layers were separated and the aqueous layer was extracted with dichloromethane (2×20 mL). The combined organic layers were dried over MgSO4, filtered, and concentrated in vacuo. The residue was purified on a preparative Phenomenex Luna C18 column using 0.1% TFA in H2O/acetonitrile as a mobile phase. The desired fractions were combined and concentrated to afford the title compound. LCMS: RT=0.624 min, >99% @ 254 nm, >98% @ 215 nm; m/z (M+H)+=509. 1H NMR (400 MHz, DMSO-d6, δ (ppm): (Note: two rotamers were observed for the desired compound in a 5:1 ratio; the integrations are reported such that for a single proton the sum of both rotamers equals 1) 8.77 (s, 1H), 8.43-8.42 (m, 1H), 8.38-8.31 (m, 1H), 8.15-8.13 (m, 0.2H (minor rotamer)), 8.00-7.98 (m, 2H), 7.91-7.74 (m, 2.6H), 7.57-7.51 (m, 2H), 7.38 (m, 0.2H (minor rotamer)), 7.31-7.29 (m, 1H), 7.20-7.11 (m, 2H), 5.64 (s, 2H), 4.89 (s, 0.4H (minor rotamer)), 4.56 (s, 1.6H (major rotamer)); HRMS calculated for C24H19N6O3SF2 (M+H)+ m/z: 509.1207, measured: 509.1205.
