1,4-Dioxane → 5-tosyl-5H-pyrrolo[2,3-b]pyrazine-2-carbaldehyde

Participants

Reaction Conditions

Reaction Steps

To a solution of (E)-2-styryl-5-tosyl-5H-pyrrolo[2,3-b]pyrazine (72.3 g, 193 mmol) in 1,4-dioxane (1500 mL) and water (300 mL) was added NaIO4 (165 g, 770 mmol) followed by OsO4 (5.00 g, 19.7 mmol). The reaction was stirred at about 25° C. for about 16 h. The reaction was concentrated under reduced pressure then was partitioned with 10% aqueous Na2S2O3 (1000 mL) and DCM (1000 mL). The organic layer was washed with water (2×500 mL) and the layers were filtered to remove undissolved precipitate and separated. The organic layer was dried over anhydrous Na2SO4, filtered through Celite®, and concentrated. The residue was purified by filtration through a pad of silica gel (1000 g) eluting with 0-5% EtOAc in DCM. The fractions were concentrated and the solid was triturated with heptane. The mixture was filtered and the filter cake was washed with heptane. This procedure was repeated for the collected undissolved precipitate. The collected solid was then dissolved in 2% EtOAc in DCM and passed through a pad of silica gel (100 g) eluting with 2% EtOAc in DCM. The filtrate was concentrated under reduced pressure. The two batches were combined to give 5-tosyl-5H-pyrrolo[2,3-b]pyrazine-2-carbaldehyde (39.1 g, 67%) as an off-white solid: LC/MS (Table 2, Method a) Rt=2.17 min; MS m/z: 302 (M+H)+.

Provenance & Evidence