Propargyl bromide → HCID 22158393, compound

HRID 1073215Notes

Reaction equation

HRID 1073215 reaction equation
[NH2:1][C:2]1[S:3][C:4]2[CH:10]=[C:9]([O:11][CH3:12])[CH:8]=[CH:7][C:5]=2[N:6]=1.[CH2:13]([Br:16])[C:14]#[CH:15]>C(O)CCC>[BrH:16].[NH:1]=[C:2]1[N:6]([CH2:15][C:14]#[CH:13])[C:5]2[CH:7]=[CH:8][C:9]([O:11][CH3:12])=[CH:10][C:4]=2[S:3]1

Participants

4

Reactant 2

HCID 7842Propargyl bromideHCID 156302-Amino-6-methoxybenzothiazole

Product 1

HCID 22158393HCID 22158393, compoundYield 302.4%

Reagents, catalysts & solvents 1

HCID 2631-ButanolSolvent

Conditions

Temperature
100 °C

Procedure

In 100 ml of n-butanol was dissolved 5.0 g of 2-amino-6-methoxybenzothiazole. With heating at 100° C., 25.0 g of propargyl bromide was dropwise added to the solution over 2 hours. The mixture was heated for a further 2 hours. After completion of the reaction, the solvent was evaporated to dryness. After the residue was crystallized with acetone, the crystals were recrystallized from isopropyl alcohol to give 25.1 g of 2-imino-6-methoxy-3-propargylbenzothiazole hydrobromide. The hydrobromide, 24.0 g, was added to sodium ethoxideethanol solution(Na, 2.0 g) followed by refluxing for 1.5 hours. After the reaction mixture was evaporated to dryness, water and ethyl acetate were added to the residue followed by separation. The residue obtained from the ethyl acetate phase was dissolved in ethanol and reacted with hydrochloric acid to convert the same into the hydrochloride. Recrystallization from 95% ethanol gave 17.3 g of 7-methoxy-2-methylimidazo[2,1-b]benzothiazole hydrochloride. The hydrochloride, 17.0 g, was added to a mixture of 10 ml of phosphorus oxychloride and 180 ml of dry dimethylformamide. After stirring at room temperature for one hour, the mixture was heated at 60° C. for 7 hours. The reaction solution was evaporated to dryness and the residue was dissolved in water. The solution was alkalized with potassium carbonate and extracted with chloroform. From the chloroform phase, 14.2 g of 3-formyl-7-methoxy-2-methylimidazo[2,1-b]benzothiazole was obtained. The obtained formyl compound, 3.7 g, was suspended in methanol and treated with 1.0 g of sodium borohydride. The reaction mixture was evaporated to dryness, and the obtained residue was recrystallized from ethanol to give 3.5 g of the title compound.

Workup

  1. temperatureThe mixture was heated for a further 2 hours
  2. customAfter completion of the reaction
  3. customthe solvent was evaporated to dryness
  4. customAfter the residue was crystallized with acetone
  5. customthe crystals were recrystallized from isopropyl alcohol

Sources & evidence

ORD record
ord-20f493f1167f4f3c81b1c5d25c35dd81
Source dataset
uspto-grants-1990_11
Patent number
US04968708

Reaction notes

Loading…