Reaction #2348106

Reaction equation

Ethyl 2-(5-bromothien-2-yl)glyoxalate

ethyl 2-(5-bromothien-2-yl)glyoxalate

NaOH

→

Intermediate 1

Yield 95.2%

2-(5-bromothien-2-yl)glyoxalic Acid

Yield 95.2%

Solvents

THF

methanol

water

Conditions

Workup

1. 1
   OtherVolatile solvents were removed by rotary evaporation
2. 2
   workup.DISSOLUTIONThe residue was dissolved in 2 L water
3. 3
   Extractionextracted with diethyl ether (250 mL)
4. 4
   Extractionextracted with diethyl ether (3×300 mL)
5. 5
   DryingThe combined diethyl ether extracts were dried over Na2SO4
6. 6
   Concentrationconcentrated in vacuo

Procedure

Ethyl 2-(5-bromothien-2-yl)glyoxalate (45.6 g, 173 mmol) from Step A was dissolved in a mixture of 100 mL THF, 100 mL methanol, and 300 mL water, then treated with 10 N NaOH (26 ml, 260 mmol) at room temperature for 20 hours. Volatile solvents were removed by rotary evaporation. The residue was dissolved in 2 L water and extracted with diethyl ether (250 mL). The aqueous layer was acidified to pH 1 with 6 N HCl, and extracted with diethyl ether (3×300 mL). The combined diethyl ether extracts were dried over Na2SO4 and concentrated in vacuo to yield 2-(5-bromothien-2-yl)glyoxalic acid, Intermediate 1 (38.7 g, 95%). The product was then recrystallized from diethyl ether. m.p. 119-120° C.; MS (M−H) 235.1; 1H NMR (300 MHz, CDCl3) d 9.00 (1H, br s), 8.15 (1H, d, J=4.2 Hz), 7.16 (1H, d, J=4.2 Hz); 13C NMR (75 MHz, CDCl3) d 173.80, 159.58, 140.14, 137.17, 132.58, 130.48; IR (KBr) 3326, 3124, 1756, 1634, 1415, 1363, 1308, 1253cm−1;

Source