Water → HCID 178503115, compound

HRID 423703Notes

Reaction equation

N([O-])=O.[Na+].[CH3:5][C:6]1[CH:11]=[C:10]([S:12][CH3:13])[CH:9]=[CH:8][C:7]=1[C:14]1[N:15]=[CH:16][C:17](N)=[N:18][CH:19]=1.[OH2:21].[OH-].[Na+]>S(=O)(=O)(O)O>[CH3:5][C:6]1[CH:11]=[C:10]([S:12][CH3:13])[CH:9]=[CH:8][C:7]=1[C:14]1[N:15]=[CH:16][C:17]([OH:21])=[N:18][CH:19]=1

Participants

Conditions

Temperature: 45 °C

Procedure

Sodium nitrite (77 mg, 1.109 mmol) was added portionwise to concentrated sulfuric acid (2 mL) at 0° C. The mixture was stirred at 45° C. until homogeneous, cooled to 0° C., and charged with a solution of 5-[2-methyl-4-(methylthio)phenyl]-2-pyrazinamine (190 mg, 0.821 mmol) in sulfuric acid (3 mL) at 0° C. The mixture was warmed to ambient temperature, stirred at ambient temperature for 15 min, then at 45° C. for 5 h. The mixture was cooled to ambient temperature, poured into water, and the pH was adjusted to ˜4 with 10N NaOH. The resulting precipitate was filtered, washed with water, and air-dried to give 100 mg (52%) of 5-[2-methyl-4-(methylthio)phenyl]-2-pyrazinol (and tautomers thereof) as a tan solid. 1H NMR (400 MHz, DMSO-d6): δ 12.61-12.37 (m, 1H), 8.08 (d, 1H, J=1.0 Hz), 7.72-7.45 (m, 1H), 7.30 (d, 1H, J=8.1 Hz), 7.22-7.06 (m, 2H), 2.48 (s, 3H), 2.30 (s, 3H); LRMS (ESI), m/z 233 (M+H).

Workup

temperaturecooled to 0° C.
temperatureThe mixture was warmed to ambient temperature
stirringstirred at ambient temperature for 15 min
temperatureThe mixture was cooled to ambient temperature
filtrationThe resulting precipitate was filtered
washwashed with water
customair-dried

Sources & evidence

ORD record: ord-7784988d90bb4f90922cb624645fb41c
Source dataset: uspto-grants-2012_01
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08101634B2

Reaction notes

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