Acetyl chloride → N-(3-bromopyridin-2-yl)acetohydrazide

Temperature

85 °C

To a solution of 0.800 g (3.38 mmol) of 2,3-dibromopyridine in 10 mL of anhydrous 1,4-dioxane was added 0.325 g (10.1 mmol) of anhydrous hydrazine and the resulting mixture was heated to 85° C. for 8 h. The reaction mixture was cooled to ambient temperature then evaporated to dryness in vacuo. The crude residue was dissolved in anhydrous dichloromethane and cooled to −78° C. in a dry ice acetone bath under an atmosphere of nitrogen. Next, 1.0 mL (6.8 mmol) of triethylamine was added followed by 0.210 g (2.72 mmol) of acetyl chloride. The resulting mixture was allowed to warm to ambient temperature over 20 min then all volatiles were removed in vacuo. The residue was suspended in 20 mL of water and extracted with ethyl acetate (3×10 mL). The combined extracts were washed with brine, dried over magnesium sulfate, filtered and evaporated to afford the title compound (0.18 g, 23%). LC-MS: m/z (ES) 230, 232 (MH)+ and 188, 190 (MH-COCH3)+.

1. temperatureThe reaction mixture was cooled to ambient temperature
2. customthen evaporated to dryness in vacuo
3. dissolutionThe crude residue was dissolved in anhydrous dichloromethane
4. temperaturecooled to −78° C. in a dry ice acetone bath under an atmosphere of nitrogen
5. temperatureto warm to ambient temperature over 20 min
6. customall volatiles were removed in vacuo
7. extractionextracted with ethyl acetate (3×10 mL)
8. washThe combined extracts were washed with brine
9. dry with materialdried over magnesium sulfate
10. filtrationfiltered
11. customevaporated

ORD record

ord-3f6acab773054fb0a99f699ac25217e1

Source dataset

uspto-grants-2013_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08399480B2