反应详情

Route B: To a solution of 2-bromo-4-methyl-5-nitropyridine (Preparation 24, 5.7 g, 26.3 mmol) in diethyl oxalate (17.9 mL) under argon was added 1,8-diazabicyclo[5,4,0]undec-7-ene (4.5 mL, 30.2 mmol) to give a dark red precipitate. Reaction mixture was stirred at rt for 4.5 h and concentrated in vacuo. Acetic acid (140 mL) was added to the residue under argon and heated to 60° C. Iron (2.94 g, 52.6 mmol) was added in small portions over a period of 1 h. The reaction mixture was heated at 80° C. for 4 h. The reaction mixture was cooled to rt and poured into water (300 mL) which gave a beige precipitate. The precipitate was isolated and washed with water. The solid obtained was dissolved in ethyl acetate (700 ml) and filtered. The filtrate was concentrated in vacuo to give the title compound. m/z (ES+)=269 [M+H]+; RT=3.39 min.

1. customto give a dark red precipitate
2. customReaction mixture
3. concentrationconcentrated in vacuo
4. additionAcetic acid (140 mL) was added to the residue under argon
5. temperatureheated to 60° C
6. temperatureThe reaction mixture was heated at 80° C. for 4 h
7. temperatureThe reaction mixture was cooled to rt
8. customgave a beige precipitate
9. customThe precipitate was isolated
10. washwashed with water
11. customThe solid obtained
12. filtrationfiltered
13. concentrationThe filtrate was concentrated in vacuo