1‐[[(4‐Methylphenyl)sulfonyl]amino]‐pyridinium inner salt

[40949-56-2] C12H12N2O2S (MW 248.30) InChI = 1S/C12H12N2O2S/c1-11-5-7-12(8-6-11)17(15,16)13-14-9-3-2-4-10-14/h2-10H,1H3 InChIKey = GHMKULDUWRCUSB-UHFFFAOYSA-N (reagent used as dipolarophiles, nitrene transfer reagent) Alternate Names: N-tosylpyridinium imide; N-tosyliminopyridinium ylide. Physical Data: mp 215 °C,1 213 °C.2 Solubility: soluble in dichloromethane, acetonitrile, ethanol, and methanol; insoluble in ethyl acetate, tetrahydrofuran, toluene, and water. Form Supplied in: yellow solid. Analysis of Reagent Purity: NMR. Preparative Methods: prepared from pyridine, O-(2,4-dinitrophenyl)hydroxylamine, and 4-toluenesulfonyl chloride (TsCl).2 To a mixture of H2O and THF (0.4 mL each for 1 mmol of pyridine) was added pyridine, followed by O-(2,4-dinitrophenyl)hydroxylamine (1.1 equiv). The resultant suspension was stirred at 40 °C for 12 h before being cooled to room temperature. The dark red mixture was treated with NaOH (2.5 N, 5 mL for 1 mmol of pyridine), followed by TsCl (1.5 equiv, in 1.6 mL of THF for 1 mmol of pyridine) dropwise. After another 4 h, the reaction was diluted with H2O and extracted with CH2Cl2. Combined extracts were washed with 2.5 N NaOH, dried over Na2SO4, filtered, and concentrated in vacuo. Purification by column chromatography gave 91% yield on a 1.24 mmol scale.2 Other methods prepared from pyridine and phenyl(tosylimino)iodinane with copper or ruthenium catalysts were also reported.1, 3 Purification: purified by column chromatography (CH2Cl2/MeOH,2 or CH2Cl2,1 or CH2Cl2/acetone3). Handling, Storage, and Precautions: stable at ambient conditions (no decomposition within 2 weeks); use in a fume hood.