Reacción #414356

Ecuación de reacción

ammonium hydroxide

2-amino-5-[(4-nitrophenyl)sulfonyl]thiazole

sodium nitrite

hypophosphoric acid

→

thiazole

Rendimiento 35.2%

5-[(4-Nitrophenyl)sulfonyl]thiazole

Rendimiento 35.2%

Disolventes

water

phosphoric acid

water

Condiciones de reacción

Tratamiento posterior

1. 1
   Temperaturato maintain the internal temperature between -5° and 5° C
2. 2
   workup.ADDITIONWhen the addition
3. 3
   workup.ADDITIONAfter the addition
4. 4
   Otrothe ice bath was removed
5. 5
   Otroreaction mixture
6. 6
   workup.STIRRINGstirred at room temperature for 3 hours during which time moderate frothing
7. 7
   Filtraciónfiltered
8. 8
   LavadoFlash chromatography of the resulting brown solid (eluted with 5% v/v ethyl acetate in methylene chloride)

Procedimiento

To a cooled (-5° C.), stirred solution of 2-amino-5-[(4-nitrophenyl)sulfonyl]thiazole (5.15 g, 18.1 mmol) in 85% phosphoric acid (200 mL) was added dropwise a solution of sodium nitrite (1.56 g, 22.6 mmol) in distilled water (10 mL) at such a rate to maintain the internal temperature between -5° and 5° C. When the addition was complete the reaction mixture was stirred for 1 hour at 0° C. then treated dropwise with 50% hypophosphoric acid (15 mL). After the addition, the ice bath was removed and reaction mixture stirred at room temperature for 3 hours during which time moderate frothing occurred. The brown solution was diluted with water (total volume=1 L), neutralized with 28% ammonium hydroxide and filtered. Flash chromatography of the resulting brown solid (eluted with 5% v/v ethyl acetate in methylene chloride) yielded the title thiazole (1.72 g, 35%) as a yellow solid; mp 168°-170° C. 1H--NMR (250 MHz, d6 --DMSO): 8.32 (d, 2H, J=12.6 Hz, aromatic), 8.45 (d, 2H, J=12.8 Hz, aromatic), 8.74 (s, 1H, aromatic), 9.578 (s, 1H, aromatic). MS (CI, CH4): 271(M+1).

Fuente