Reaction #2139933

Reaction equation

potassium hydroxide

Phosphorus oxychloride

dimethylformamide

10-ethylphenothiazine

DMF

→

10-Ethylphenothiazine-3-carbaldehyde

Conditions

Workup

1. 1
   TemperatureThe reaction mixture was refluxed at 80° C. for 24 hours
2. 2
   ExtractionThe product was extracted with chloroform
3. 3
   ExtractionThe chloroform extract
4. 4
   Dryingwas dried with anhydrous sodium sulfate
5. 5
   Filtrationfiltered
6. 6
   workup.DISTILLATIONdistilled
7. 7
   OtherThe product was recrystallized from methanol
8. 8
   Otherwas 94-95° C.
9. 9
   Other(crystallized from methanol)

Procedure

Phosphorus oxychloride (POCl3, 3.7 ml, 0.04 mol, obtained from Aldrich) was added dropwise to 4.4 ml (0.06 mol) of dry dimethylformamide (DMF) at 0° C. under a nitrogen atmosphere. This solution was warmed up slowly to room temperature. Next, a solution of 5 g (0.02 mol) of 10-ethylphenothiazine in 5 ml dry DMF was added dropwise. The reaction mixture was refluxed at 80° C. for 24 hours and poured into ice water. This solution was neutralized with potassium hydroxide until the pH reached 6-8. The product was extracted with chloroform. The chloroform extract was dried with anhydrous sodium sulfate, filtered, and distilled. The product was recrystallized from methanol. The yield of 10-ethylphenothiazine-3-carbaldehyde was 3.7 g (66%). The melting point of the product was 94-95° C. (crystallized from methanol). The 1H-NMR spectrum (100 MHz) of the product in CDCl3 was characterized by the following chemical shifts (δ, ppm): 1.50 (t, J=7.0 Hz, 3H, CH3); 4.02 (q, J=7.0 Hz, 2H, CH2); 6.95-6.39 (m, 5H, Ar), 7.52-7.70 (m, 2H, Ar), 9.83 (s, 1H, CHO).

Source