Hydrochloric Acid → 2-(3-methyl-butyl)-6-thiophen-2-yl-2H-pyridazine-3,5-dione

HRID 421501Notes

Reaction equation

C(OC([C:6]1[C:7](=[O:23])[N:8]([CH2:18][CH2:19][CH:20]([CH3:22])[CH3:21])[N:9]=[C:10]([C:13]2[S:14][CH:15]=[CH:16][CH:17]=2)[C:11]=1[OH:12])=O)C.Cl>O1CCOCC1.ClCCl>[CH3:21][CH:20]([CH3:22])[CH2:19][CH2:18][N:8]1[C:7](=[O:23])[CH2:6][C:11](=[O:12])[C:10]([C:13]2[S:14][CH:15]=[CH:16][CH:17]=2)=[N:9]1

Participants

Conditions

Temperature: 100 °C

Procedure

5-Hydroxy-2-(3-methyl-butyl)-3-oxo-6-thiophen-2-yl-2,3-dihydro-pyridazine-4-carboxylic acid ethyl ester (0.3 g, 0.892 mmol, prepared as described in WO06066079A2) was dissolved in 1,4-dioxane (10 mL) and a 1.0 M aqueous hydrochloric acid solution (10 mL) was added. The mixture stirred in a sealed tube at 100° C. for 4 h. Upon cooling, the mixture was concentrated in vacuo to afford a thick oil. The oil was dissolved in dichloromethane (15 mL) and passed through a plug of silica gel (Merck silica gel 60, 40-63 μm), eluting with ethyl acetate. Upon concentrating, the desired product, 2-(3-methyl-butyl)-6-thiophen-2-yl-2H-pyridazine-3,5-dione (0.215 g, 0.814 mmol) was obtained as a thick oil. 1H NMR (400 MHz, DMSO-d6) δ: 0.91 (6H, d, J=6.2 Hz), 1.49-1.61 (3H, m), 4.03 (2H, t, J=7.1 Hz), 6.09 (1H, s), 7.10 (1H, dd, J1=8.6 Hz, J2=0.0 Hz), 7.58 (1H, d, J=5.4 Hz), 7.77 (1H, dd, J1=4.0 Hz, J2=1.6 Hz), 12.02 (1H, s).

Workup

temperatureUpon cooling
concentrationthe mixture was concentrated in vacuo
customto afford a thick oil
washeluting with ethyl acetate
concentrationUpon concentrating

Sources & evidence

ORD record: ord-d66fecee50cf4314b71def6ee1ba7b00
Source dataset: uspto-grants-2012_01
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08097613B2

Reaction notes

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