Diethyl squarate → 3-Ethoxy-4-[2-hydroxy-3-(1-hydroxyethyl)phenylamino]cyclobut-3-ene-1,2-dione

HRID 1528162Notes

Reaction equation

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

Participants

Conditions

Temperature: 60 °C

Procedure

A mixture of 1.16 g (7.6 mmol, 1 eq) of 2-amino-6-(1-hydroxyethyl)phenol and 5.15 g (30.3 mmol, 4 eq) of 3,4-diethoxy-3-cyclobutene-1,2-dione in 50 ml of ethanol was heated at 60° C. for 18 hours. The reaction medium was evaporated and the residue was chromatographed on silica gel (column puriFlash IR-50SI/300G, Spot II) eluted with heptane/ethyl acetate (gradient). 800 mg of 3-ethoxy-4-[2-hydroxy-3-(1-hydroxyethyl)phenylamino]cyclobut-3-ene-1,2-dione were obtained in the form of an orange solid. Yield=38%.

Workup

customThe reaction medium was evaporated
customthe residue was chromatographed on silica gel (column puriFlash IR-50SI/300G, Spot II)
washeluted with heptane/ethyl acetate (gradient)

Sources & evidence

ORD record: ord-c1a4aacd224d4b6a9e61cce8847591a1
Source dataset: uspto-grants-2015_07
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US09090596B2

Reaction notes

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