Reaktion #56029

Reaktionsgleichung

2,3-dihydro-8-nitro-3-oxo-5H-pyrido[3,4-b][1,4]benzothiazine-4-carbonitrile

hydrochloric acid

→

8-amino-2,3-dihydro-3-oxo-5H-pyrido[3,4-b][1,4]benzothiazine-4-carbonitrile

Lösungsmittel

acetic acid

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturunder reflux
2. 2
   Temperaturchilled
3. 3
   FiltrationInsoluble solids are filtered out
4. 4
   workup.DISSOLUTIONdissolved in a mixture of 1100 parts of sulfinylbis[methane] with 200 parts of water
5. 5
   workup.ADDITIONdiluted with 1 volume of water
6. 6
   FiltrationThe precipitate which forms is filtered off
7. 7
   Sonstigeconsecutively recrystallized from (1)
8. 8
   workup.ADDITIONa mixture of sulfinylbis[methane] and methanol and (2)
9. 9
   workup.ADDITIONa mixture of sulfinylbis[methane], N,N-dimethylformamide, and water

Vorschrift

To a suspension of 25 parts of a 1:1 solvate of 2,3-dihydro-8-nitro-3-oxo-5H-pyrido[3,4-b][1,4]benzothiazine-4-carbonitrile in 1000 parts of glacial acetic acid is added a solution of 75 parts of stannous chloride dihydrate in 230 parts of 28% hydrochloric acid. The resultant mixture is heated at the boiling point under reflux with stirring for 2 hours, then chilled. Insoluble solids are filtered out and dissolved in a mixture of 1100 parts of sulfinylbis[methane] with 200 parts of water. This solution is basified with concentrated ammonium hydroxide and thereupon diluted with 1 volume of water. The precipitate which forms is filtered off and consecutively recrystallized from (1) a mixture of sulfinylbis[methane] and methanol and (2) a mixture of sulfinylbis[methane], N,N-dimethylformamide, and water to give 8-amino-2,3-dihydro-3-oxo-5H-pyrido[3,4-b][1,4]benzothiazine-4-carbonitrile melting above 305°.

Quelle