反应详情

A mixture of 5-bromo-pyridine-3-sulfonic acid (Example B.2 step 1) (7.14 g, 30 mmol), phosphorus pentachloride (9.68 g, 47 mmol) and phosphorus oxychloride (20 mL) was heated to reflux for 4 h (according to J. Org. Chem. 1989, 54(2), 389. ). The reaction mixture was concentrated to dryness to give a yellow semisolid, dissolved in ice water and tert-butyl-methyl-ether, and cautiously added sat. NaHCO3-sol. until neutralized, saturated with solid NaCl, separated phases, dried organic layer over Na2SO4. Removal of the solvent in vacuum gave the title compound as a yellow solid (7.57 g, 98%). MS (EI) 254.9 [(M)+], 256.9 [(M+2)+] and 258.9 [(M+4)+]; mp 64° C.

1. temperaturewas heated
2. temperatureto reflux for 4 h (according to J. Org. Chem. 1989, 54(2), 389. )
3. concentrationThe reaction mixture was concentrated to dryness
4. customto give a yellow semisolid
5. customseparated phases, dried organic layer over Na2SO4
6. customRemoval of the solvent in vacuum