Triethylamine → N'-(6-Chloro-5-(trimethylsilyl)pyridazin-3-yl)-2-fluorobenzohydrazide

Temperature

-4 °C

To a stirred mixture of 3-chloro-6-hydrazino-4-(trimethylsilyl)pyridazine (6.34 g, 29.3 mmol) and anhydrous triethylamine (4.9 ml, 35.2 mmol) in anhydrous diethyl ether (100 ml), cooled under nitrogen to −4° C., was added dropwise, over 13 min, 2-fluorobenzoyl chloride (3.5 ml, 29.4 mmol) keeping the temperature below 5° C. The thick mixture was then stirred for 30 min at 0-5° C., then quenched with anhydrous methanol (1 ml). The mixture was diluted with hexane (100 ml) and filtered. The collected solid was washed with diethyl ether (2×25 ml), then water (100 ml), then dissolved in dichloromethane (300 ml) and methanol (20 ml), washed with saturated aqueous NaCl (100 ml), dried (Na2SO4), and evaporated in vacuo to leave 9.72 g (98%) of the title compound as a pale brown solid; 1H NMR (360 MHz, CDCl3) δ 0.36 (9H, s), 7.07 (1H, s), 7.20 (1H, dd, J=11.7 and 8.2 Hz), 7.30 (1H, t, J=7.6 Hz), 7.55 (1H, m), 8.00 (1H, br s), 8.07 (1H, td, J=7.7 and 1.8 Hz), 9.19 (1H, br s); MS (ES+) m/e 339/341 [MH]+, 217/219 [M-COC6H4F+2H]+.

1. additionwas added dropwise, over 13 min
2. customthe temperature below 5° C
3. customquenched with anhydrous methanol (1 ml)
4. additionThe mixture was diluted with hexane (100 ml)
5. filtrationfiltered
6. washThe collected solid was washed with diethyl ether (2×25 ml)
7. dissolutionwater (100 ml), then dissolved in dichloromethane (300 ml)
8. washmethanol (20 ml), washed with saturated aqueous NaCl (100 ml)
9. dry with materialdried (Na2SO4)
10. customevaporated in vacuo

ORD record

ord-58331e2039b54e62b587a27f10efbe2a

Source dataset

uspto-grants-2004_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06828322B2