Hydrochloric Acid → 7-Ethyl-2,3-dioxo-1,2,3,4-tetrahydrothieno[2,3-b]pyrazine-6-carboxylic acid

HRID 1974973Notes

Reaction equation

C([O:3][C:4]([C:6]1[S:16][C:9]2[NH:10][C:11](=[O:15])[C:12](=[O:14])[NH:13][C:8]=2[C:7]=1[CH2:17][CH3:18])=[O:5])C.[OH-].[Na+].Cl.O>O1CCCC1>[C:4]([C:6]1[S:16][C:9]2[NH:10][C:11](=[O:15])[C:12](=[O:14])[NH:13][C:8]=2[C:7]=1[CH2:17][CH3:18])([OH:5])=[O:3]

Participants

Conditions

Temperature: 0 °C

Procedure

A mixture of 6-ethoxycarbonyl-7-ethylthieno[2,3-b]-pyrazine-2,3(1H,4H)-dione (24.5 g, 91 mmol) and sodium hydroxide (10.96 g, 274 mmol) in 50% aqueous tetrahydrofuran (340 ml) was heated at 50°-60° C. for 16 h. The reaction mixture was cooled to 0° C. and acidified (pH=2) with hydrochloric acid. Water (300 ml) was added, the precipitate filtered off, washed with water and dried. Purification was performed by dissolving in 2 M sodium hydroxide solution, extraction with dichloromethane and precipitation of the aqueous phase with hydrochloric acid. The precipitate was filtered off, washed with water and dried to afford 14.2 g (65%) of the title compound. M.p. 230°-232° C. 1H-NMR (DMSO-d6, δ) : 1. 09 (t, 3H) 3.03 (q, 2H), 11.90 (s, 1H), 12.50 (br. s, 1H), 12.92 (br. s, 1H).

Workup

temperaturewas heated at 50°-60° C. for 16 h
filtrationthe precipitate filtered off
washwashed with water
customdried
customPurification
dissolutionby dissolving in 2 M sodium hydroxide solution
extractionextraction
customwith dichloromethane and precipitation of the aqueous phase with hydrochloric acid
filtrationThe precipitate was filtered off
washwashed with water
customdried

Sources & evidence

ORD record: ord-b31c7dc688a745e4adf4b86aef5bf2e3
Source dataset: uspto-grants-1994_02
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US05284847

Reaction notes

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