2,3-Dihydro-1,4-benzothiazine → 4-nitroso-3,4-dihydro-2H-benzo[b][1,4]thiazine

HRID 51032Notes

Reaction equation

HRID 51032 reaction equation
[S:1]1[C:6]2[CH:7]=[CH:8][CH:9]=[CH:10][C:5]=2[NH:4][CH2:3][CH2:2]1.[N:11]([O-])=[O:12].[Na+]>C(O)(=O)C.O>[N:11]([N:4]1[C:5]2[CH:10]=[CH:9][CH:8]=[CH:7][C:6]=2[S:1][CH2:2][CH2:3]1)=[O:12]

Participants

5

Reactant 2

HCID 1510642,3-Dihydro-1,4-benzothiazineHCID 23668193Sodium Nitrite

Product 1

HCID 218596124-nitroso-3,4-dihydro-2H-benzo[b][1,4]thiazineYield 101.1%

Reagents, catalysts & solvents 2

HCID 176Acetic AcidSolventHCID 962WaterSolvent2×

Procedure

To a solution of 3,4-dihydro-2H-1,4-benzothiazine (50.0 g, 330.8 mmol) in acetic acid (170 mL.), cooled at −10° C. in an ice/acetone bath, was added sodium nitrite (27.4 g, 397.1 mmol) in 75 mL of water over 35 min. After the addition, the mixture was warmed to room temperature and stirred for additional 1.5 hours. Cold water (150 mL) was added and the resulting mixture was extracted with dichloromethane (4×250 mL). The combined organic extracts were washed with water and brine, dried over anhydrous sodium sulfate, and concentrated to dryness under reduced pressure to give 4-nitroso-3,4-dihydro-2H-1,4-benzothiazine as a semi-solid (60.26 g, 101%), which was used in the next step without further purification. 1H NMR (300 MHz, DMSO-d6) δ2.99-3.05 (m, 2 H), 4.16-4.24 (m, 2 H), 7.15-7.31 (m, 3 H), 7.88-7.97 (m, 1 H) ppm.

Workup

  1. additionAfter the addition
  2. extractionthe resulting mixture was extracted with dichloromethane (4×250 mL)
  3. washThe combined organic extracts were washed with water and brine
  4. dry with materialdried over anhydrous sodium sulfate
  5. concentrationconcentrated to dryness under reduced pressure

Sources & evidence

ORD record
ord-d151e825197c428e9fc93a7dd78784e0
Source dataset
uspto-grants-2004_03
Patent number
US06713471B1

Reaction notes

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