Reaction #1772009

Reaction equation

4-methylaminobenzoic acid

5-methoxy-2-aminothiophenol

K2CO3

→

6-Methoxy-2-(4-methylaminophenyl)benzothiazole

Yield 22.3%

Conditions

Workup

1. 1
   TemperatureThe reaction mixture was then cooled to room temperature
2. 2
   FiltrationThe precipitate was filtered under reduced pressure
3. 3
   OtherThe crude product was re-crystallized twice from acetone/water and THF/water

Procedure

A mixture of 4-methylaminobenzoic acid (11.5 g, 76.2 mmol) and 5-methoxy-2-aminothiophenol (12.5, g, 80 mmol) was heated in PPA (˜30 g) to 170° C. under N2 atmosphere for 1.5 hr. The reaction mixture was then cooled to room temperature and poured into 10% K2CO3 solution. The precipitate was filtered under reduced pressure. The crude product was re-crystallized twice from acetone/water and THF/water followed by the treatment with active with carbon to give 4.6 g (21%) of 6-Methoxy-2-(4-methylaminophenyl)benzothiazole as a yellow solid. 1HNMR (300 MHz, acetone-d6) δ: 7.84 (d, J=8.7 Hz, 2H, H-2′ 6′), 7.78 (dd, J1=8.8 Hz, J2=1.3 Hz, 1H, H-4), 7.52 (d, J=2.4 Hz, 1H, H-7), 7.05 (dd, J1=8.8 Hz, J2=2.4 Hz, H-5), 6.70 (d, J=7.6 Hz, 2H, H-3′ 5′), 5.62 (s, 1H, NH), 3.88 (s, 3H, OCH3), 2.85 (d, J=6.2 Hz, 3H, NCH3)

Source