Hydrochloric Acid → Pirquinozol

HRID 1763511Notes

Reaction equation

HRID 1763511 reaction equation
[O:1]=[C:2]1[N:11]2[N:12]=[C:13]([C:15](OCC)=[O:16])[CH:14]=[C:10]2[C:9]2[CH:8]=[CH:7][CH:6]=[CH:5][C:4]=2[NH:3]1.[BH4-].[Li+].Cl>O>[OH:16][CH2:15][C:13]1[CH:14]=[C:10]2[N:11]([C:2](=[O:1])[NH:3][C:4]3[CH:5]=[CH:6][CH:7]=[CH:8][C:9]=32)[N:12]=1

Participants

5

Reactant 3

HCID 313Hydrochloric AcidHCID 4148881Lithium borohydrideHCID 1360233445,6-Dihydro-5-oxopyrazolo[1,5-c]quinazoline-2-carboxylic acid ethyl ester

Product 1

HCID 135449340PirquinozolYield 84.1%

Reagents, catalysts & solvents 1

HCID 962WaterSolvent

Conditions

Temperature
0 °C

Procedure

500 mg (0.0019 mole) of 5,6-dihydro-5-oxopyrazolo[1,5-c]quinazoline-2-carboxylic acid, ethyl ester, prepared as described in Example 2A, is suspended in 10 ml distilled tetrahydrofuran and treated with 99.6 mg (0.0039 mole or 2 equivalents) of 85% lithium borohydride at room temperature. The mixture is stirred overnight (~20 hours), cooled down to 0° C., treated with 4.5 ml of 1.0 N hydrochloric acid and stirred for 30 minutes. The mixture is then diluted with water (25 ml), stirred for 10 minutes and filtered. The white precipitates are dried in a vacuum oven at ~70° for 1.5 hours to give 344 mg of title compound, m.p. 289°-290°; 84% yield. An additional 31.3 mg is obtained from the filtrate on addition of an equal volume of methylene chloride.

Workup

  1. distillationdistilled tetrahydrofuran
  2. stirringstirred for 30 minutes
  3. stirringstirred for 10 minutes
  4. filtrationfiltered
  5. customThe white precipitates
  6. customare dried in a vacuum oven at ~70° for 1.5 hours

Sources & evidence

ORD record
ord-6a52a9fc37e44f83bbb7f819a2bdb9b0
Source dataset
uspto-grants-1978_09
Patent number
US04112096

Reaction notes

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