Hydrochloric Acid → 10,10a-Dihydroimidazo[1,5-b]isoquinoline-1,3(2H,5H)-dione

HRID 1414287Notes

Reaction equation

HRID 1414287 reaction equation
[CH2:1]1[C:10]2[C:5](=[CH:6][CH:7]=[CH:8][CH:9]=2)[CH2:4][CH:3]([C:11]([OH:13])=O)[NH:2]1.[O-:14][C:15]#[N:16].[K+].Cl>C(O)(=O)C.O>[C:11]1(=[O:13])[CH:3]2[N:2]([CH2:1][C:10]3[CH:9]=[CH:8][CH:7]=[CH:6][C:5]=3[CH2:4]2)[C:15](=[O:14])[NH:16]1

Participants

6

Reactant 3

HCID 313Hydrochloric AcidHCID 954891,2,3,4-Tetrahydroisoquinoline-3-carboxylic acidHCID 11378442Potassium cyanate

Product 1

HCID 1491483210,10a-Dihydroimidazo[1,5-b]isoquinoline-1,3(2H,5H)-dioneYield 49.3%

Reagents, catalysts & solvents 2

HCID 176Acetic AcidSolventHCID 962WaterSolvent

Procedure

To a suspension of 53.1 g (0.30 mole) of 1,2,3.4-tetrahydroisoquinoline-3-carboxylic acid in 1000 ml glacial acetic acid was added quickly a solution of 48.6 g (0.60 mole) of potassium cyanate in 150 ml water. The mixture was stirred and heated on a steam bath at 90°-95° for 90 min and all solids dissolved. 3N hydrochloric acid (2400 ml) was added and the resulting solution was stirred and refluxed for 20 hr. The solution was filtered while hot through a coarse sintered glass funnel to remove mechanical impurities and the filtrate was stored in the refrigerator for 18 hrs to deposit 44 g of the crude product. Recrystallization from 1400 ml alcohol gave 29.9 g (49%) of the cyclized material, m.p. 225°-231°. Further recrystallization from alcohol gave the analytical sample, m.p. 227°-230°.

Workup

  1. temperatureheated on a steam bath at 90°-95° for 90 min
  2. dissolutionall solids dissolved
  3. stirringthe resulting solution was stirred
  4. temperaturerefluxed for 20 hr
  5. filtrationThe solution was filtered while hot through a coarse sintered glass funnel
  6. customto remove mechanical impurities
  7. customRecrystallization from 1400 ml alcohol

Sources & evidence

ORD record
ord-d5f7162b4f5144758dc1572b74acba55
Source dataset
uspto-grants-1977_01
Patent number
US04001245

Reaction notes

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