Urea → 4,5-Dihydrooxazolo[4,5-f]quinolin-2-amine

HRID 34658Notes

Reaction equation

HRID 34658 reaction equation
[N:1]1[C:10]2[C:9]3[CH:11]=[CH:12][CH:13]=[N:14][C:8]=3[CH2:7][CH2:6][C:5]=2C=[N:3][C:2]=1N.Br.N1C(=[O:27])C=CC2C=1C=CCC=2.NC(N)=O.[OH-].[NH4+]>O>[N:1]1[C:10]2[C:9]3[CH:11]=[CH:12][CH:13]=[N:14][C:8]=3[CH2:7][CH2:6][C:5]=2[O:27][C:2]=1[NH2:3]

Participants

6

Reactant 4

HCID 1176UreaHCID 14923Ammonium HydroxideHCID 142338515,6-Dihydropyrido[2,3-h]quinazolin-2-amineHCID 131715686HCID 131715686, compound

Product 1

HCID 212982074,5-Dihydrooxazolo[4,5-f]quinolin-2-amine

Reagents, catalysts & solvents 1

HCID 962WaterSolvent

Procedure

A solution of 6-bromo-7,8-dihydro-5(6H- quinolinone, hydrobromide, 10.0 g (32.5 mmol), (Example 2), in 150 ml of hot water is refluxed with 6.0 g (100 mmol) of urea for 24 hours. After cooling, the solution is made basic with concentrated ammonium hydroxide and extracted with 2×250 ml of dichloromethane. The organic extract is concentrated and the residue is chromatographed (1% ammonium hydroxide, 99% ethyl acetate) to separate the two products, 4,5-dihydrooxazolo[4,5-f]quinolin-2-amine (Example 28) and 4,5-dihydrooxazolo[5,4-f]quinolin-2-amine (Example 27).

Workup

  1. temperatureAfter cooling
  2. extractionextracted with 2×250 ml of dichloromethane
  3. extractionThe organic extract
  4. concentrationis concentrated
  5. customthe residue is chromatographed (1% ammonium hydroxide, 99% ethyl acetate)
  6. customto separate the two products, 4,5-dihydrooxazolo[4,5-f]quinolin-2-amine (Example 28) and 4,5-dihydrooxazolo[5,4-f]quinolin-2-amine (Example 27)

Sources & evidence

ORD record
ord-d64be7665ee6405f8c3baf85e1f53801
Source dataset
uspto-grants-1988_08
Patent number
US04762843

Reaction notes

Loading…