Carbon Dioxide → 3-Imino-8,9-dimethoxy-5,6-dihydro-3H-[1,3]thiazolo[4,3-a]isoquinoline-1-carbonitrile

HRID 261021Notes

Reaction equation

HRID 261021 reaction equation
[C:1]([CH:3]=[C:4]1[C:13]2[C:8](=[CH:9][C:10]([O:16][CH3:17])=[C:11]([O:14][CH3:15])[CH:12]=2)[CH2:7][CH2:6][NH:5]1)#[N:2].C([O-])(O)=O.[Na+].BrBr.C(=O)=O.[C:28]([S-:30])#[N:29].[K+]>CO>[C:1]([C:3]1[S:30][C:28](=[NH:29])[N:5]2[CH2:6][CH2:7][C:8]3[C:13](=[CH:12][C:11]([O:14][CH3:15])=[C:10]([O:16][CH3:17])[CH:9]=3)[C:4]=12)#[N:2]

Participants

7

Reactant 5

HCID 280Carbon DioxideHCID 24408BromineHCID 419389(6,7-Dimethoxy-3,4-dihydroisoquinolin-1(2H)-ylidene)acetonitrileHCID 516872Potassium thiocyanateHCID 516892Sodium Bicarbonate

Product 1

HCID 1627773-Imino-8,9-dimethoxy-5,6-dihydro-3H-[1,3]thiazolo[4,3-a]isoquinoline-1-carbonitrileYield 86.8%

Reagents, catalysts & solvents 1

HCID 887MethanolSolvent2×

Conditions

Temperature
60 °C

Procedure

57.5 g. (0.25 moles) of 1-cyanomethylene-1,2,3,4-tetrahydro-6,7-dimethoxy-isoquinoline, 21.5 g. (0.255 moles) of sodium hydrocarbonate and 375 ml. of methanol are introduced into a 2 l. flask equipped with a stirrer, reflux condenser, thermometer and addition funnel. The mixture is heated to boiling with stirring, thereafter it is cooled to 60° C., and 40 g. (0.25 moles) of bromine are added dropwise to the solution within 20 minutes. During the addition carbon dioxide evolves and leaves the system. Thereafter the solution is boiled, and a solution of 40 g. (about 0.4 moles) of potassium rhodanide in 300 ml. of methanol is added. The separated precipitate temporarily dissolves, thereafter a loose, voluminous precipitate separates. The mixture is boiled for 1.5 hours, thereafter left to stand in a refrigerator overnight. The precipitate is filtered off, suspended in 500 ml. of water, and 20 ml. of 1 N sodium hydroxide solution are added to the suspension. The precipitate is filtered again, and washed with 3×100 ml. of water. 62.3 g. (86.8%) of 1-cyano-3-imino-3,4,5,6-tetrahydro-8,9-dimethoxy-1,3-thiazolo[4,3-a]isoquinoline are obtained; m.p.: 229°-230° C. (decomposition).

Workup

  1. customflask equipped with a stirrer
  2. temperaturereflux condenser
  3. additionthermometer and addition funnel
  4. temperatureThe mixture is heated
  5. customleaves the system
  6. dissolutionThe separated precipitate temporarily dissolves
  7. waitleft
  8. customto stand in a refrigerator overnight
  9. filtrationThe precipitate is filtered off
  10. additionof 1 N sodium hydroxide solution are added to the suspension
  11. filtrationThe precipitate is filtered again
  12. washwashed with 3×100 ml

Sources & evidence

ORD record
ord-adb29c9067194539baf7cefef9fba1da
Source dataset
uspto-grants-1979_08
Patent number
US04163786

Reaction notes

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