Reaction #324398

Reaction equation

5-[4-(tert-butyldimethylsilyloxy)phenyl]-3-(thieno[3,2-b]thiophen-2-yl)pyrazin-2-amine

5-[4-(tert-Butyldimethylsilyloxy)phenyl]-3-(thieno[3,2-b]thiophen-2-yl)pyrazin-2-amine

2-[4-(tert-butyldimethylsilyloxy)phenyl]acetyl chloride

water

→

Compound 11k

Yield 58.2%

2-[4-(tert-Butyldimethylsilyloxy)phenyl]-N-[5-{4-(tert-butyldimethylsilyloxy)phenyl}-3-(thieno[3,2-b]thiophen-2-yl)pyrazin-2-yl]acetamide

Yield 58.2%

Solvents

pyridine

Conditions

Workup

1. 1
   Otherprepared above at 0° C.
2. 2
   Temperaturethe mixture was heated
3. 3
   TemperatureAfter cooling to room temperature
4. 4
   Extractionthe product was extracted with ethyl acetate (100 mL×3)
5. 5
   ExtractionThe combined organic extract
6. 6
   Washwas washed successively with water (200 mL) and brine (200 mL)
7. 7
   Dryingby drying over anhydrous sodium sulfate
8. 8
   FiltrationAfter filtration and concentration under reduced pressure
9. 9
   Otherthe residue was purified by column chromatography (silica gel 30 g, n-hexane/ethyl acetate=3/1)

Procedure

Under an argon atmosphere, to a mixture of 5-[4-(tert-butyldimethylsilyloxy)phenyl]-3-(thieno[3,2-b]thiophen-2-yl)pyrazin-2-amine (7k) (250 mg, 569 μmol and 4-(dimethylamino)pyridine (12.3 mg, 101 μmol) dissolved in anhydrous pyridine (15 mL) was added 2-[4-(tert-butyldimethylsilyloxy)phenyl]acetyl chloride (10) prepared above at 0° C. and the mixture was heated with stirring at 50° C. for 13 hours. After cooling to room temperature, to this was added water and the product was extracted with ethyl acetate (100 mL×3). The combined organic extract was washed successively with water (200 mL) and brine (200 mL), followed by drying over anhydrous sodium sulfate. After filtration and concentration under reduced pressure, the residue was purified by column chromatography (silica gel 30 g, n-hexane/ethyl acetate=3/1) to give Compound 11k (228 mg, 331 μmol, 58.2%) as a yellow solid. Rf=0.26 (n-hexane/ethyl acetate=3/1); 1H NMR (400 MHz, DMSO-d6) δ 0.17 (s, 6H), 0.22 (s, 6H), 0.93 (s, 9H), 0.95 (s, 9H), 3.67 (s, 2H), 6.78-6.86 (AA′BB′, 2H), 6.96-7.04 (AA′BB′, 2H), 7.20-7.30 (AA′BB′, 2H), 7.41 (d, 1H, J=5.2 Hz), 7.57 (s, 1H), 7.73 (d, 1H, J=5.2 Hz), 8.04-8.13 (AA′BB′, 2H), 8.92 (s, 1H), 10.69 (s, 1H); IR (KBr, cm−1) 527, 635, 702, 779, 837, 918, 1007, 1074, 1169, 1256, 1362, 1445, 1508, 1603, 1655, 2857, 2886, 2928, 2955, 3211.

Source