3-(2-Ethoxy-3,4-dioxocyclobut-1-enylamino)-2-hydroxybenzoic acid → 2-Hydroxy-3-(2-{[(5-methylfuran-2-yl)-(3-methyloxetan-3-yl)methyl]amino}-3,4-dioxocyclobut-1-enylamino)benzoic acid

Participants

Reaction Conditions

Reaction Steps

453 mg (2.5 mmol, 1.5 eq) of C-(5-methylfuran-2-yl)-C-(3-methyloxetan-3-yl)methylamine were added to 471 mg (1.7 mmol, 1 eq) of 3-(2-ethoxy-3,4-dioxocyclobut-1-enylamino)-2-hydroxybenzoic acid dissolved under hot conditions in 50 ml of methanol. The reaction medium was heated at 50° C. for 18 hours and then at 60° C. for 7 days. The methanol was evaporated off and the residue was chromatographed on silica gel (column puriFlash IR50SI-120G, Spot II) eluted with dichloromethane/methanol (gradient). The solid was taken up with a little ethyl acetate, filtered and dried under vacuum at 55° C. 310 mg of 2-hydroxy-3-(2-{[(5-methylfuran-2-yl)-(3-methyloxetan-3-yl)methyl]amino}-3,4-dioxocyclobut-1-enylamino)benzoic acid were obtained in the form of a brown solid. (Mp=180-185° C.). Yield=44%. LC/MS: 97.08% [412].

Provenance & Evidence