Hydrochloric Acid → 4-chloro-5-(cyclopentylmethoxy)pyridazin-3(2H)-one

HRID 2381354Notes

Reaction equation

[Cl:1][C:2]1[C:3](=[O:21])[N:4](C2CCCCO2)[N:5]=[CH:6][C:7]=1[O:8][CH2:9][CH:10]1[CH2:14][CH2:13][CH2:12][CH2:11]1.Cl.[OH-].[Na+]>CO.O>[Cl:1][C:2]1[C:3](=[O:21])[NH:4][N:5]=[CH:6][C:7]=1[O:8][CH2:9][CH:10]1[CH2:14][CH2:13][CH2:12][CH2:11]1

Participants

Conditions

Temperature: 110 °C

Procedure

A solution of 4-chloro-5-cyclopentylmethoxy-2-(tetrahydro-pyran-2-yl)-2H-pyridazin-3-one (1.63 g, 5.21 mmol) in methanol (10 mL, 0.52M) was treated with a 6N aqueous hydrochloric acid solution (4.4 mL). The reaction solution was heated to 110° C., where it stirred for 2.5 h and was then allowed to cool to 25° C. The reaction was then diluted with water (100 mL) and brought to basic pH with a 4N aqueous sodium hydroxide solution. This solution was extracted with methylene chloride (1×100 mL). The aqueous layer was then acidified with a 3N aqueous hydrochloric acid solution. The resulting white precipitate was collected by filtration, washed with water, and dried in vacuo to afford 4-chloro-5-cyclopentylmethoxy-2H-pyridazin-3-one (1.06 mg, 89%) as a white solid; ES+-HRMS m/e calcd for C10H13N2O2Cl [M+H+] 229.0739, found 229.0738. 1H NMR (400 MHz, DMSO-d6) δ ppm 1.26-1.40 (m, 2H), 1.47-1.68 (m, 4H), 1.70-1.82 (m, 2H), 2.22-2.38 (m, 1H), 4.22 (d, J=6.8 Hz, 2H), 8.19 (s, 1H), 13.28 (brs, 1H).

Workup

temperatureto cool to 25° C
extractionThis solution was extracted with methylene chloride (1×100 mL)
filtrationThe resulting white precipitate was collected by filtration
washwashed with water
customdried in vacuo

Sources & evidence

ORD record: ord-5d8abed1551f4dca8fbed0fb1b1be068
Source dataset: uspto-grants-2012_09
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08258134B2

Reaction notes

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