Butyric Acid → 7-Methyl-2-propyl-1H-imidazo[4,5-b]pyridine

HRID 1029552Notes

Reaction equation

HRID 1029552 reaction equation
[C:1](O)(=O)[CH2:2][CH2:3][CH3:4].[NH2:7][C:8]1[C:13]([NH2:14])=[C:12]([CH3:15])[CH:11]=[CH:10][N:9]=1.[NH4+].[OH-]>>[CH3:15][C:12]1[CH:11]=[CH:10][N:9]=[C:8]2[N:7]=[C:1]([CH2:2][CH2:3][CH3:4])[NH:14][C:13]=12

Participants

4

Reactant 3

HCID 264Butyric AcidHCID 14923Ammonium HydroxideHCID 3174954-Methylpyridine-2,3-diamine

Product 1

HCID 150208527-Methyl-2-propyl-1H-imidazo[4,5-b]pyridineYield 95%

Conditions

Temperature
100 °C

Procedure

A mixture of butyric acid (6.57 mL, 71.9 mmol), 2,3-diamino-4-picoline (8.05 g, 65.4 mmol) (Lappin, G. R., Slezak, F. B. J. Am. Chem. Soc. (1950) 72, 7806-7) and polyphosphoric acid (50 g) was heated to 100° C. with stirring for 3 hours. The reaction was monitored by tlc of NH4OH neutralized aliquots. Basification (NH4OH), extraction (CH2Cl2, 4×50 mL), drying (K2CO3), purification (by filtering through 100 g SiO2, EtOAc elution), and concentration gave 10.0 g (95%) of the title compound as an amorphous tan solid which was judged pure by 1H NMR and tlc: mp 110°-112° C. (without recrystallization); 1H NMR (300 MHz, CDCl3) δ8.13 (d, 1H, J=5 Hz), 7.01 (d, 1H, J=5 Hz), 3.01 (t, 2H, J=7.8 Hz), 2.67 (s, 3H), 2.07-1.93 (m, 2H), 1.06 (t, 3H, J=7.5 Hz).

Workup

  1. extractionBasification (NH4OH), extraction (CH2Cl2, 4×50 mL)
  2. customdrying
  3. custom(K2CO3), purification (by filtering through 100 g SiO2, EtOAc elution), and concentration

Sources & evidence

ORD record
ord-aa2aec6244d146bb9e98fee0e4a4b4e0
Source dataset
uspto-grants-1992_04
Patent number
US05102880

Reaction notes

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