6-chloro-3-(2-ethoxy-3,4-dioxocyclobut-1-enylamino)-2-hydroxy-N,N-dimethylbenzamide → 6-chloro-2-hydroxy-N,N-dimethyl-3-(2-{[(R)-(5-methylfuran-2-yl)-(3-methyloxetan-3-yl)methyl]amino}-3,4-dioxocyclobut-1-enylamino)benzamide

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Reaction Steps

A mixture of 412 mg (2.27 mmol, 1.1 eq) of C—(R)-(5-methylfuran-2-yl)-C-(3-methyloxetan-3-yl)methylamine (prepared in EXAMPLE 50, steps 1 to 4) and 700 mg (2.07 mmol, 1 eq) of 6-chloro-3-(2-ethoxy-3,4-dioxocyclobut-1-enylamino)-2-hydroxy-N,N-dimethylbenzamide in 45 ml of methanol was stirred at ambient temperature for 3 days. The methanol was evaporated off and the residue was taken up with ethyl acetate and washed with a 1 M aqueous sodium dihydrogen phosphate solution. The organic phase was dried over anhydrous sodium sulfate, filtered and concentrated. The residue (0.90 g) was chromatographed on silica gel (80 g prepacked column, eluent dichloromethane/methanol, from 0 to 10% of methanol). 520 mg of 6-chloro-2-hydroxy-N,N-dimethyl-3-(2-{[(R)-(5-methylfuran-2-yl)-(3-methyloxetan-3-yl)methyl]amino}-3,4-dioxocyclobut-1-enylamino)benzamide were obtained in the form of an ochre solid. Yield=53%. Mp=165-167° C.

Provenance & Evidence