Yield:42456-75-7 45%

Reaction Conditions:

with nitric acid at -5 - 30;

Steps:

1.A

2-Chloro-5-acetylthiophene (80.3 g, 0.5 mol) was added in portions to fuming nitric acid (500 mL) cooled to -5 ⁰C with an ice/methanol bath. On completion of addition the reaction was removed from the cold bath and stirred at ambient temperature for 30 minutes before the reaction mixture was poured into ice water (4 L). After stirring for 10 minutes the solid which formed was collected by filtration and washed with water (500 mL). The solid was then dissolved in dichloromethane (500 mL) the water was separated and the organic solution was dried (MgSO₄). Removal of the solvent under reduced pressure gave an orange solid. The crude material was re-crystallized from IMS (350 mL) to give the title product as a light brown solid (46.89 g, 45% yield). ¹H NMR (CDCl₃) δ: 8.07 (IH, s), 2.58 (3H, s).

References:

WO2010/114881,2010,A1 Location in patent:Page/Page column 26