4-Bromobenzohydrazide → 2-(4-Bromophenyl)-5-methyl-1,3,4-oxadiazole

Temperature

60 °C

4-Bromo-benzoic acid hydrazide (12.90 g, 60 mmol) and N,N-dimethylacetamide dimethyl acetal (12 mL, 82.0 mmol) were dissolved in N,N-dimethylformamide (100 mL) and the solution heated to 60° C. for 2 hours. The solution was concentrated in vacuo and the residue taken up in toluene (80 mL) and treated with para-toluenesulfonic acid monohydrate (200 mg, 1.50 mmol). The mixture was heated to reflux for 2 hours, allowed to cool, and the product crystallised from the solution and was collected by filtration. The crude product was washed with ether and dried in vacuo to yield a white solid. The filtrate was concentrated in vacuo and the residue combined with the white solid, dissolved in toluene (50 mL) and treated with para-toluenesulfonic acid monohydrate (100 mg, 0.75 mmol). The mixture was heated to reflux for 3 hours, allowed to cool and concentrated in vacuo. The residue was purified by column chromatography on silica gel eluting with pentane:ethyl acetate 80:20 to 40:60 to yield the title product, 12.00 g.

1. concentrationThe solution was concentrated in vacuo
2. temperatureThe mixture was heated
3. temperatureto reflux for 2 hours
4. temperatureto cool
5. customthe product crystallised from the solution
6. filtrationwas collected by filtration
7. washThe crude product was washed with ether
8. customdried in vacuo
9. customto yield a white solid
10. concentrationThe filtrate was concentrated in vacuo
11. dissolutiondissolved in toluene (50 mL)
12. temperatureThe mixture was heated
13. temperatureto reflux for 3 hours
14. temperatureto cool
15. concentrationconcentrated in vacuo
16. customThe residue was purified by column chromatography on silica gel eluting with pentane:ethyl acetate 80:20 to 40:60

ORD record

ord-8e58207e9f6c447a8b0c8bf39306cb91

Source dataset

uspto-grants-2007_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07291640B2