Acetic Acid → N'-[(6-chloro-3,4-dihydro-4-methyl-3-oxopyrazin-2-yl)aminocarbonyl]-N,N-dimethyl-1,2-benzenedisulfonamide

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Reaction Steps

1,8-Diazabicyclo[5.4.0]undec-7-ene (0.30 mL, 2.00 mmol) was added dropwise over two minutes to a mixture of N,N-dimethyl-1,2-benzenedisulfonamide (0.53 g, 2.00 mmol) and phenyl (6-chloro-3,4-dihydro-4-methyl-3-oxopyrazin-2-yl)carbamate (0.56 g, 2.00 mmol) in anhydrous acetonitrile (20 mL) under nitrogen. After 3 hours at room temperature, glacial acetic acid (0.12 mL, 2.10 mmol) was added. The solvent was rotary evaporated and the residue was chromatographed on a column of silica gel using a solvent mixture of 1:1 dichloromethane-ether containing 2 mL/L acetic acid as eluant. The appropriate fractions were evaporated to leave 0.76 g of N'-[(6-chloro-3,4-dihydro-4-methyl-3-oxopyrazin-2-yl)aminocarbonyl]-N,N-dimethyl-1,2-benzenedisulfonamide as a crystalline solid melting at 227°-230° C.

Provenance & Evidence