Diethyl squarate → 4-(2-Ethoxy-3,4-dioxo-cyclobut-1-enylamino)-3-ethylbenzonitrile

HRID 260799

Reaction equation

HRID 260799 reaction equation
[NH2:1][C:2]1[CH:9]=[CH:8][C:5]([C:6]#[N:7])=[CH:4][C:3]=1[CH2:10][CH3:11].[CH2:12]([O:14][C:15]1[C:16](=O)[C:17](=[O:22])[C:18]=1[O:19]CC)[CH3:13]>C(#N)C.C(OCC)(=O)C>[O:19]=[C:18]1[C:17](=[O:22])[C:16]([NH:1][C:2]2[CH:9]=[CH:8][C:5]([C:6]#[N:7])=[CH:4][C:3]=2[CH2:10][CH3:11])=[C:15]1[O:14][CH2:12][CH3:13]

Participants

5

Reactant 2

HCID 123228Diethyl squarate2×HCID 27353304-Amino-3-ethylbenzonitrile

Product 1

HCID 199729184-(2-Ethoxy-3,4-dioxo-cyclobut-1-enylamino)-3-ethylbenzonitrileYield 34%

Reagents, catalysts & solvents 2

HCID 6342AcetonitrileSolventHCID 8857Ethyl AcetateSolvent

Conditions

Temperature
150 °C

Procedure

4-Amino-3-ethylbenzonitrile (0.86 g, 5.88 mmol) and 3,4-diethoxy-3-cyclobutene-1,2-dione (1.0 g, 5.88 mmol) in acetonitrile (2 mL) was heated in an oil bath at 110° C. for 21 hours. 3,4-Diethoxy-3-cyclobutene-1,2-dione (0.5 g, 2.9 mmol) was added to the reaction mixture and the temperature of the oil bath increased to 150° C. After 48 hours the reaction mixture was cooled to room temperature, then diluted with ethyl acetate and filtered. The filtrate was concentrated and the resulting solid was taken up in ethyl acetate (5 mL) and sonicated. Filtration gave 0.54 g (34%) of 4-(3,4-dioxo-2-ethoxy-cyclobut-1-enylamino)-3-ethylbenzonitrile as a light brown solid: 1H NMR (DMSO-d6): δ 10.56 (br s, 1H), 7.70 (br s overlapping a doublet at δ 7.69, 2H), 7.30 (d, 1H), 4.71 (q, 2H), 2.74 (q, 2H), 1.37 (t, 3H), 1.15 (t, 3H).

Workup

  1. temperatureAfter 48 hours the reaction mixture was cooled to room temperature
  2. filtrationfiltered
  3. concentrationThe filtrate was concentrated
  4. customsonicated
  5. filtrationFiltration

Sources & evidence

ORD record
ord-72ab03e7554b4b568883a777a1c795e1
Source dataset
uspto-grants-1996_06
Patent number
US05530025

Linked notes

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