3,4-Diaminopyridine → 2-(2,3-Difluorophenyl)-3H-imidazo[4,5-c]pyridine

HRID 1992530Notes

Reaction equation

O=P12OP3(OP(OP(O3)(O1)=O)(=O)O2)=O.[NH2:15][C:16]1[CH:17]=[N:18][CH:19]=[CH:20][C:21]=1[NH2:22].[F:23][C:24]1[C:32]([F:33])=[CH:31][CH:30]=[CH:29][C:25]=1[C:26](O)=O.[OH-].[Na+]>CS(O)(=O)=O>[F:23][C:24]1[C:32]([F:33])=[CH:31][CH:30]=[CH:29][C:25]=1[C:26]1[NH:15][C:16]2[CH:17]=[N:18][CH:19]=[CH:20][C:21]=2[N:22]=1

Participants

Conditions

Temperature: 190 °C

Procedure

Phosphorous pentoxide (24.56 g) was dissolved in methanesulfonic acid (165.8 mL) at 50° C. with stirring. To the solution, 3,4-diaminopyridine (12.3 g, 0—11 moles) and 2,3-difluorobenzoic acid (19.4 g, 0.12 moles) were added. The reaction mixture was heated to 190° C. for 3 hours. The reaction was done three times. The reaction mixtures was cooled to 50° C. and poured into ice with stirring. At this stage, all three batches were combined. The reaction mixture was neutralized by the addition of NaOH with stirring until the pH is 8. Solid material precipitated out of solution, was collected by filtration and air-dried. The final product was re-crystallized from ethanol/water twice to yield 36 g of 2-(2,3-difluorophenyl)-3H-imidazo[4,5-c]pyridine. 1H 300 Mhz (CD3OD) sigma 7.3-7.42 (m, 1p); 7.43-7.58 (m, 1p); 7.70 (d, 1p); 8.0 (m, 1p); 8.34 (d, 1p); and 8.95 (s, 1p). LC/MS data M/z=232.

Workup

customThe reaction mixtures
temperaturewas cooled to 50° C.
additionpoured into ice
stirringwith stirring
stirringwith stirring until the pH is 8
customSolid material precipitated out of solution
filtrationwas collected by filtration
customair-dried
customThe final product was re-crystallized from ethanol/water twice

Sources & evidence

ORD record: ord-133a58efd9a64f3f8104a4b39474ae41
Source dataset: uspto-grants-2010_01
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US07648998B2

Reaction notes

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