6-nitrothieno[3,2-b]pyridin-7-ol synthesis

Yield:905735-40-2 85%

Reaction Conditions:

Stage #1: thieno[3,2-b]pyridin-7-olwith tetrabutylammonium nitrate in dichloromethane at -5;
Stage #2: with trifluoroacetic anhydride in dichloromethane at -5 - 20;

Steps:

1.1 Step 1. 6-Nitrothieno[3,2-b]pyridin-7-ol

N,N,N-Tributylbutan-1-aminium nitrate (from Aldrich, 9.1 g, 30 mmol) dissolved in methylene chloride (100 mL) was added dropwise to a stirred solution of thieno[3,2-b]pyridin-7-ol (from Aldrich, 3.0 g, 20 mmol) in methylene chloride (100 mL) at -5° C. Trifluoroacetic anhydride (4.5 mL, 32 mmol) was added while maintaining the temperature below 0° C. The resulting mixture was then stirred at -5° C. for 30 min and at room temperature overnight. The reaction mixture was concentrated, diluted with ether, filtered. The solid collected was washed with water and then ether/methanol (MeOH) mixture (1:1), and air-dried to give the desired product (3.3 g, 85%). LCMS calculated for C₇H₅N₂O₃S (M+H)⁺: m/z=197.0. Found: 196.9.

References:

US2014/121198,2014,A1 Location in patent:Paragraph 0546-0548