Hydrochloric Acid → 2,3-dihydro-4H-1,4-benzothiazin-4-amine hydrochloride

HRID 1764908Notes

Reaction equation

HRID 1764908 reaction equation
[H-].[Al+3].[Li+].[H-].[H-].[H-].[N:7]([N:9]1[C:14]2[CH:15]=[CH:16][CH:17]=[CH:18][C:13]=2[S:12][CH2:11][CH2:10]1)=O.[ClH:19]>C1COCC1.CCOC(C)=O>[ClH:19].[S:12]1[C:13]2[CH:18]=[CH:17][CH:16]=[CH:15][C:14]=2[N:9]([NH2:7])[CH2:10][CH2:11]1

Participants

6

Reactant 3

HCID 313Hydrochloric AcidHCID 21226445Aluminium lithium hydrideHCID 218596124-nitroso-3,4-dihydro-2H-benzo[b][1,4]thiazine

Product 1

HCID 227356922,3-dihydro-4H-1,4-benzothiazin-4-amine hydrochlorideYield 73%

Reagents, catalysts & solvents 2

HCID 8028TetrahydrofuranSolvent2×HCID 8857Ethyl AcetateSolvent2×

Procedure

To a solution of lithium aluminum hydride in THF (1 M) (331 mL, 331 mmol) was added 4-nitroso-3,4-dihydro-2H-1,4-benzothiazine (59.6 g, 330.8 mmol) in 150 mL of THF at −15° C. over 2 hours under nitrogen atmosphere. After the addition, the mixture was slowly warmed to room temperature. After 4 hours, the reaction was complete (TLC, 70:30 hexanes, ethyl acetate) and hydrated sodium sulfate (approximately 150 g) was added carefully until bubbling ceased. The resulting slurry mixture was filtered and washed with THF (5×50 mL). The organic filtrate was concentrated under reduced pressure to give a red oil. This residue was taken in EtOAc (300 mL), cooled to 0° C., and treated with 1 M solution of ethereal hydrochloric acid (230 mL). The precipitate obtained was collected by filtration, washed with EtOAc (50 mL) and dried under vacuum to give 2,3-dihydro-4H-1,4-benzothiazin-4-amine hydrochloride as a white solid (48.8 g, 73%). 1H NMR (300 MHz, CDCl3) δ3.21-3.32 (m, 2H), 3.69-3.78 (m, 2H), 4.70-5.11 (br-s, 2H), 6.98-7.36 (m, 4H) ppm.

Workup

  1. additionAfter the addition
  2. additionwas added carefully
  3. customuntil bubbling
  4. filtrationThe resulting slurry mixture was filtered
  5. washwashed with THF (5×50 mL)
  6. concentrationThe organic filtrate was concentrated under reduced pressure
  7. customto give a red oil
  8. temperaturecooled to 0° C.
  9. customThe precipitate obtained
  10. filtrationwas collected by filtration
  11. washwashed with EtOAc (50 mL)
  12. customdried under vacuum

Sources & evidence

ORD record
ord-cf79c98e50f54bea8bc168acbcb3c8af
Source dataset
uspto-grants-2007_06
Patent number
USRE039679E1

Reaction notes

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